Type 2 diabetes

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DIABETES MELLITUS

Diabetes mellitus is a failure to control blood sugar levels so that they become too high. It is classified into two categories. Type 1 diabetes (also called juvenile diabetes) is characterized by an acute destruction of insulin-secreting beta cells in the pancreas by autoantibodies. Insulin is a hormone essential to maintaining blood sugar at a normal level. Diabetes results in the abolition of insulin secretion by the pancreas, severe hyperglycemia (high blood sugar ) and production of ketones. Type 2 diabetes (also called adult onset diabetes) is characterized by a gradually increasing blood sugar level resulting from a combination of resistance to the action of insulin at the cellular level and a gradual decline of insulin secretion by the pancreas.

Diabetes mellitus is a common disease in the older population. The vast majority of elderly subjects have type 2 diabetes, which means that the degree of hyperglycemia is variable and rarely results in the production of ketones. Since the degree of hyperglycemia is variable and elderly subjects are often not aware of the symptoms of high blood sugar (see below), there may be a few years of asymptomatic disease before a diagnosis of diabetes is made.

Prevalence

The most recent health and nutrition survey in the United States demonstrated that the prevalence of diabetes approaches 20 percent in Caucasian persons over age seventy, and may be as high as 50 percent in certain ethnic groups (Harris et al.). Canadian data suggest a similar picture with about 12 percent of people age sixty-five and older affected (Roc et al.). As of 2000 in North America, the group of people over sixty-five represents about 13 percent of the total population. Assuming that the trend of aging persists, this group will likely represent around 21 percent of the population by 2020. If the prevalence of diabetes remains the same, there is likely to be a marked increase in the absolute number of elderly diabetic patients by the middle of twenty-first century.

Clinical presentation and diagnosis

At least half of elderly individuals with diabetes are unaware that they have the disease, and often the diagnosis is made after the complications of the disease are established (Harris et al.). Although the reasons for late diagnosis of diabetes are unclear, it may be related to a lack of awareness of the diagnostic criteria on the part of physicians, lack of interaction by elderly patients with a physician, and the fact that elderly patients frequently do not manifest the classic symptoms of hyperglycemia: excessive secretion of urine, excessive thirst, and excessive appetite. Symptoms do not generally occur until blood glucose levels are substantially elevated, possibly because the level at which sugar spills into the urine increases with age. When patients do have symptoms, they are often nonspecific (e.g., failure to thrive, low energy, confusion, frequent urination, with or without incontinence, various infections), and may not always trigger the measurement of a plasma glucose level or a consultation with a physician. This phenomenon, along with the fact that identification and management of diabetes can relieve many of these symptoms, improve the quality of life, and prevent or delay subsequent chronic illnesses, highlights the importance of screening for diabetes in elderly individuals.

The diagnosis of diabetes may be accomplished by measuring fasting plasma glucose. It is currently recommended that fasting glucose be measured every three years in elderly persons and yearly in persons with risk factors for the development of diabetes, such as obesity, hypertension, and a strong family history of diabetes. The diagnosis of diabetes is made by a fasting plasma glucose of at least 7.0 millimol/liter on two occasions. A diagnosis can also be made when a patient is found to have a glucose of at least 11.1 millimol/liter two hours after a 75 gram oral glucose load (American Diabetes Association, 1997), but for practical reasons a glucose tolerance test is not generally performed.

Complications

As a result of high blood sugar levels; abnormalities of lipid levels, blood pressure regulation, and blood coagulation; and oxidative stress, elderly patients with diabetes develop a number of complications. The long-term complications of diabetes are classified as microvascular (mainly kidney and eye problems) and macrovascular (vascular problems related to heart, brain, and lower limbs). Diabetes is a leading cause of blindness, kidney failure leading to hemodialysis, heart problems (angina and infarction), and limb amputation in the elderly diabetic population.

Treatment

All clinicians agree that blood glucose levels should be controlled sufficiently well to reduce the symptoms of hyperglycemia. There is less consensus regarding the optimal degree of blood sugar control in elderly diabetic patients. This is due in part to the fact that no randomized controlled trials involving elderly subjects have definitively assessed whether tight blood glucose control reduces the risk of disease and disability in this age group. The United Kingdom Prospective Diabetes Study (UKPDS) recruited middle-aged patients with type 2 diabetes and randomized them to either intensive blood glucose control with metformin, sulfonylurea, or insulin or a control group with conventional treatment. The UKPDS data did demonstrate that improved glycemic control reduces the risk of microvascular complications related to diabetes, and perhaps macrovascular complications in middle-aged patients. Furthermore, in observational studies of elderly subjects, improved glycemic control is associated with a reduced risk of microvascular and macrovascular complications related to diabetes (Kuusisto et al.; Morisaki et al.), as well as with improved cognitive function (Meneilly et al.). Based on these data, it is recommended that goals for control in elderly patients should be less than 7 millimol/liter before meals and less than 10 millimol/liter after meals.

Nonpharmacological intervention. Achieving optimal blood sugar control in elderly persons with diabetes is challenging. These patients take numerous medications, have multiple comorbidities, and often live in challenging social situations. Because of the complex nature of these patients and the need for lifestyle modifications, a team approach is essential. A structured diabetes teaching program will improve blood sugar control, compliance with therapy, and quality of life in older patients. Self-monitoring of blood sugar level at home is possible with a portable device called a glucometer. The self-monitoring of blood sugar constitutes a key aspect of diabetic management. Levels of HbA1c (glycosilated hemoglobin) and/or fructosamine are the standard laboratory measures of long-term glycemic control in older individuals, and should be assessed at regular intervals (Meltzer et al.).

Exercise programs have been shown to improve the sense of well-being, glucose levels, and lipid levels in elderly patients with diabetes (Agurs-Collins et al.). Unfortunately, concomitant health problems often prevent elderly patients from participating in exercise programs, and optimal activity levels may be difficult to achieve. Thus exercise programs of even low and moderate intensity are of value in selected elderly patients.

Elderly patients with diabetes have diets that are too low in complex carbohydrates and too high in saturated fats, and they frequently do not comply with a diabetic diet. As noted above, multidisciplinary interventions have been shown to improve compliance with dietary therapy in aged diabetics. For community-dwelling elderly subjects, weight loss programs have been shown to result in substantial improvements in blood sugar control (Reaven et al.). In contrast, for frail elderly nursing home residents, diabetic diets complicate and increase the cost of care, and do not improve blood sugar control.

Pharmacological intervention. The principal metabolic defect in lean elderly patients with diabetes is profound impairment in glucose-induced insulin secretion. Medications that stimulate insulin secretion, such as sulfonylureas, have been widely used for the treatment of diabetes in elderly patients that is not controlled with dietary therapy. This kind of medication is associated with an increased risk of hypoglycemia, especially in the elderly. Chlorpropamide and glyburide are the sulfonylureas associated with the greatest risk of hypoglycemia in the elderly. Observational studies and small, randomized controlled trials suggest that glipizide and gliclazide are associated with a lower risk of hypoglycemia in the older population with diabetes (Brodows; Tessier et al.). In general, initial doses of these drugs should be half those for younger people, and should be increased more slowly. The role of newer insulin-stimulating drugs, such as repaglinide, remains to be determined for elderly patients with diabetes.

The UKPDS suggests that metformin, a member of the biguanide family, is an effective agent in obese middle-aged patients, and may be more beneficial than sulfonylureas in reducing the risk of morbid events. The main effect of metformin is to reduce insulin resistance. This drug results in substantial improvements in blood sugar control in obese elderly patients (Lalau et al.). Metformin should not be given to patients with creatinine values (blood indicator of kidney function) above 180 microns/liter, chronic liver disease, or significant congestive heart failure. Based on clinical experience, sulfonylureas and metformin can often be given in combination to elderly patients with diabetes to improve blood sugar control.

Because of their ability to improve insulin resistance, thiazolidinediones (pioglitazone and rosiglitazone) may also be a useful class of drugs for obese elderly patients. This class of drug improves insulin resistance. Pending the results of further studies in the elderly, this class of drugs should be reserved for the treatment of obese elderly patients whose blood sugar is not optimally controlled with another kind of antidiabetic medication. When thiazolidinediones are prescribed for the elderly, liver function should be monitored at regular intervals.

Alpha glucosidase inhibitors are a class of drugs that interfere with the action of the enzymes responsible for the digestion of complex carbohydrates and disaccharides at the brush border of the intestine. This class of drugs slows the absorption of glucose through the small intestine. Acarbose is the first of these drugs released for clinical use. A study has been published on the efficacy of this drug for elderly diabetes patients (Meneilly et al.). At present, acarbose should be considered as first-line therapy for lean elderly patients with a modest increase in fasting glucose levels.

Insulin therapy substantially improves blood sugar control with no adverse effect on the quality of life in patients who are inadequately controlled by oral agents (Tovi and Engfeldt). Elderly patients can make substantial errors when trying to mix different kinds of insulin in the same syringe (e.g., the rapid-acting R or Toronto insulin with the intermediate-acting N or NPH insulin). For this reason, insulin preparations that do not require mixing are preferable for them. In type 2 diabetes, insulin therapy is usually started ". . .with one dose of intermediate acting insulin in addition to pills given at different times of the day such as metformin and glyburide." However, many patients who are started on one daily dose of insulin need a second injection in order to control blood sugar.

Management of hypertension and excess lipids

Traditional risk factors for cardiovascular disease, such as smoking, hypertension, and excess lipids, are associated with an increased risk of diabetes-related complications in the elderly. Modification of these risk factors may reduce the risk of these complications.

Studies suggest that treatment of hypertension with drugs such as the thiazide diuretics and calcium channel blockers reduces mortality and the risk of vascular complications related to diabetes in the elderly (Tuomilehto et al.; Curb et al.). In the Systolic Hypertension in the Elderly Patient study (SHEP), patients with systolic hypertension and type 2 diabetes who were treated with a thiazide diuretic, had a significantly lower incidence of cardiovascular events than subjects receiving a placebo. The absolute risk reduction with active treatment compared with the placebo was twice as great for diabetic as for nondiabetic patients who participated in this study. The Systolic Hypertension in Europe Trial (SystEur) undertook a similar subgroup analysis of older patients with both hypertension and type 2 diabetes. Among the nondiabetic participants who were started on a calcium-channel blocker, nitrendipine, a 55 percent reduction of mortality was observed compared to the placebo group. In the group receiving active treatment, reduction of overall mortality was significantly higher among the diabetic patients than among the nondiabetic ones.

There are no data from randomized trials in the elderly diabetic population to determine the benefits of treatment of excess lipids. Subgroup analysis of middle-aged patients with diabetes (Pyorala et al.; Goldberg et al.) and subjects sixty-five or older (LIPID Study Group) who enrolled in prevention trials suggesting that reduction of low-density lipoprotein (LDL) cholesterol can significantly decrease vascular events in this population.

Perspective

Considering the aging trend in American society, an increased prevalence of diabetes is expected among the elderly population. The economic and sociological impacts of this health problem will dramatically increase by the middle of the twenty-first century. More research will be necessary to understand the disease and the mechanisms involved in the progression of associated complications.

Daniel Tessier Tamas FÜrlÖp Graydon S. Meinelly

See also Cholesterol; Diet; Disease Presentation; Heart Disease; High Blood Pressure.

BIBLIOGRAPHY

Agurs-Collins, T. D.; Kumanyika, S. K.; Ten Have, T. R. et al. "A Randomized Controlled Trial of Weight Reduction and Exercise for Diabetes Management in Older African-American Subjects." Diabetes Care 20 (1997): 15031511.

American Diabetes Association. Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. "Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus" 20 (1997): 11831197. Brodows, R. G. "Benefits and Risks with Glyburide and Glipizide in Elderly NIDDM Patients." Diabetes Care 15 (1992): 7580.

Curb, J. D.; Pressel, S. L.; Cutler, J. et al. "Effect of Diuretic Based Antihypertensive Treatment on Cardiovascular Risk in Older Diabetic Patients with Isolated Systolic Hypertension." Journal of the American Medical Association 276 (1996): 18861892.

Goldberg, R. B.; Mellies, M. J.; Sacks, F. et al. "Cardiovascular Events and Their Reduction with Pravastatin in Diabetic and Glucose-Intolerant Myocardial Infarction Survivors with Average Cholesterol Levels: Subgroup Analyses on the Cholesterol and Recurrent Events (CARE) Trial." Circulation 98 (1998): 25132519.

Harris, M. I.; Flegal, K. M.; Cowie, C. C. et al. "Prevalence of Diabetes, Impaired Fasting Glucose, and Impaired Glucose Tolerance in U.S. Adults. The Third National Health and Nutrition Examination Survey, 19881994." Diabetes Care 21 (1998): 5181924.

Kuusisto, J.; Mykkanen, L.; Pyorala, K. et al. "NIDDM and Its Metabolic Control Predict Coronary Heart Disease in Elderly Subjects." Diabetes 43 (1994): 960967.

Lalau, J. D.; Vermersch, A.; Hary, L. et al. "Type 2 Diabetes in the Elderly: An Assessment of Metformin." International Journal of Clinical Pharmacology and Therapeutic Toxicology 28 (1990): 329332.

LIPID Study Group. "Prevention of Cardiovascular Events and Death with Pravastatin in Patients with Coronary Heart Disease and a Broad Range of Initial Cholesterol Levels." New England Journal of Medicine 339 (1998): 13491357.

Meneilly, G. S.; Cheung, E.; Tessier, D. et al. "The Effect of Improved Glycemic Control on Cognitive Functions in the Elderly Patient with Diabetes." Journal of Gerontology 48 (1993): M117M121.

Meneilly, G. S.; Ryan, E. A.; Radzuik, eJ. et al. "Effect of Acarbose on Insulin Sensitivity in Elderly Patients with Diabetes." Diabetes Care 23 (2000): 11621167.

Meltzer S.; Leiter, L.; Daneman, D.; Gerstein,HJ. C. et al. "1998 Clinical Practice Guidelines for the Management of Diabetes in Canada." Canadian Medical Association Journal 159 (8 suppl) (1998): S1S29.

Morisaki, N.; Watanabe, S.; Kobayashi, J. et al. "Diabetic Control and Progression of Retinopathy in Elderly Patients: Five-Year Follow-up Study." Journal of the American Geriatric Society 42 (1994): 142145.

Pyorala, K.; Pedersen, T. R.; Kjekshus, J. et al. "Cholesterol Lowering with Simvastatin Improves Prognosis of Patients with Coronary Heart Disease: A Subgroup Analysis of the Scandinavian Simvastatin Survival Study (4S)." Diabetes Care 20 (1997): 614620.

Reaven, G. M., and Staff of the Palo Alto GRECC Aging Study Unit. "Beneficial Effects of Weight Loss in Older Patients with NIDDM." Journal of American Geriatric Society 33 (1985): 9395.

Rockwood, K.; Tar, M. H.; Phillips, S.; and Mcdowell, I. "Prevalence of Diabetes Mellitis in Elderly People in Canada." Age Ageing 27 (1998): 573577.

Tessier, D.; Dawson, K.; Tetrault, J. P. et al. "Glibenclamide vs. Gliclazide in Type 2 Diabetes of the Elderly." Diabetic Medicine 11 (1994): 974980.

Tovi, J., and Engfeldt, P. "Well-being and Symptoms in Elderly Type 2 Diabetes Patients with Poor Metabolic Control: Effect of Insulin Treatment." Practical Diabetes International 15 (1998): 7377.

Tuomilehto, J.; Rastenyte, D.; Birkenhager, W. H. et al. "Effects of Calcium-Channel Blockade in Older Patients with Diabetes and Systolic Hypertension. Systolic Hypertension in Europe Trial Investigators." New England Journal of Medicine 340 no. 9 (1999): 677684.

United Kingdom Prospective Diabetes Study. "Intensive Blood Glucose Control with Sulphonylureas or Insulin Compared with Conventional Treatment and Risk of Complications in Patients with Type 2 Diabetes (UKPDS33)." Lancet 352, no. 9131 (12 September 1998): 837853.

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DIABETES MELLITUS

The term "diabetes mellitus" represents a group of conditions characterized by abnormally high blood glucose levels (hyperglycemia). In 1997, nearly 16 million people in the United States had diabetes; approximately 10.3 million were diagnosed with the conditions, while an estimated 5.4 million were undiagnosed. Diabetes may be complicated by uncontrolled hyperglycemia, and treated diabetes may be complicated by abnormally low blood glucose levels (hypoglycemia). Maternal diabetes is associated with an increased incidence of major birth defects. Over time, diabetes may cause complications involving the eyes (retinopathy), kidneys (nephropathy), and nerves (neuropathy). Diabetes is also associated with an increased incidence of cardiovascular disease, including stroke, heart attack, and peripheral vascular disease. In the United States today, diabetes is a leading cause of birth defects, blindness, kidney failure, and nontraumatic leg amputations. It is also a major contributor to cardiovascular disease. Diabetes is the seventh leading cause of death in the United States, and medical care for people with diabetes is estimated to cost over $100 billion per year.

When diabetes is associated with marked hyperglycemia, it produces characteristic symptoms and signs; particularly increased thirst (polydipsia), increased urination (polyuria), and unexplained weight loss. At other times, hyperglycemia sufficient to cause changes in the eyes, kidneys, and nerves, and to increase the risk of cardiovascular disease, may be present without clinical symptoms. During this asymptomatic period, an abnormality in glucose metabolism may be demonstrated by measuring fasting venous glucose or venous glucose after an oral glucose challenge.

DIAGNOSIS

When a patient is symptomatic and the plasma glucose is unequivocally elevated, a diagnosis of diabetes presents no difficulty. When a patient is without clinical symptoms, a diagnosis of diabetes is more difficult. According to a 1997 American Diabetes Association (ADA) report, there are three ways to diagnose diabetes (see Table 1). All require measurement of venous plasma glucose, and each must be confirmed on a subsequent day by any one of the three methods. In general, the oral glucose tolerance test is not recommended for routine clinical use and is performed only in patients with elevated but nondiagnostic fasting plasma-glucose levels with a high index of suspicion for diabetes.

CLASSIFICATION

Once a diagnosis of diabetes mellitus is established, it is necessary to differentiate the various forms of the syndrome. Prior to 1979, diabetes was

Table 1

Criteria for the Three Methods Diagnosis of Diabetes Mellitus in Nonpregnant Adults
* In the absence of unequivocal hyperglycemia with acute metabolic decompensation, these criteria should be confirmed by repeat testing on a different day. The third measure (OGTT) is not recommended for routine clinical use.
source: Expert Committee on the Diagnosis and Classification of Diabetes Mellitus: Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus (1997). Diabetes Care 20:1183-1197.
  1. Symptoms of diabetes plus casual plasma glucose concentration 200 mg/dL (11.1 mmol/L).* Casual is defined as any time of day without regard to time since last meal. The classic symptoms of diabetes include polyuria, polydipsia, and unexplained weight loss.
  2. Fasting Plasma Glucose 126 mg/dL (7.0 mmol/L).* Fasting is defined as no caloric intake for at least 8 hours.
  3. 2-hour Plasma Glucose 200 mg/dL (11.1 mmol/L) during an Oral Glucose Tolerance Test (OGTT).* The test should be performed using a glucose load containing the equivalent of 75 g. anhydrous glucose dissolved in water.

classified on the basis of age at diagnosis as either juvenile-onset diabetes mellitus (JODM) or adult-onset diabetes mellitus (AODM). In the late 1970s and early 1980s, a new classification system recognized two major forms of diabetes: insulin-dependent diabetes mellitus (IDDM or type I diabetes) and non-insulin-dependent diabetes mellitus (NIDDM or type II diabetes). In 1997, the American Diabetes Association recommended modifications to this classification system that eliminated the terms "insulin-dependent diabetes mellitus" and "non-insulin-dependent diabetes mellitus" and their acronyms. The terms "type 1" and "type 2" were retained, with Arabic numerals replacing the Roman numerals. Other specific types of diabetes were also recognized.

Type 1 diabetes is caused by pancreatic beta cell (B-cell) destruction. Immune-mediated type 1 diabetes results from cell-mediated autoimmune destruction of the B-cells of the pancreatic islets. This type of diabetes also has strong genetic or human leukocyte antigen (HLA) associations that can be either predisposing or protective. Another form of type 1 diabetes, termed "idiopathic" type 1 diabetes, is strongly inherited but lacks immunologic evidence for B-cell autoimmunity and is not HLA-associated. Most patients with

Table 2

Incidence of Diagnosed Diabetes per 1,000 Population by Age, United States, 1994.
Age Group
04 4564 65+ Total
source: Centers for Disease Control and Prevention (1997). Diabetes Surveillance, 1997. Atlanta, GA: CDC.
1.59 7.20 8.84 3.61

idiopathic type 1 diabetes are of African or Asian descent.

Type 1 diabetes accounts for approximately 5 percent of diagnosed diabetes in the United Statesapproximately 500,000 Americans have type 1 diabetes. Type 1 diabetes commonly occurs in childhood and adolescence, but it can occur at any age. Patients with type 1 diabetes are prone to ketoacidosis (decompensated diabetes with hyperglycemia and presence of abnormal acids [ketones] in the blood). Many affected patients have no family history of diabetes. Although most patients with type 1 diabetes are lean when they are diagnosed, the presence of obesity is not incompatible with the diagnosis.

Type 2 diabetes is characterized by both impairment of insulin secretion and defects in insulin action. It is often unclear which abnormality is the primary cause of hyperglycemia. Although patients with this type of diabetes may have insulin levels that appear normal or elevated, insulin levels are always low relative to the elevated plasma glucose levels. Thus, insulin secretion is defective in these patients and insufficient to compensate for the degree of insulin resistance. Although the specific origin of type 2 diabetes is not known, autoimmune destruction of B-cells does not occur. Although type 2 diabetes is associated with a strong genetic predisposition, the genetics of this form of diabetes are complex and not clearly defined.

Type 2 diabetes accounts for approximately 95 percent of diagnosed diabetes in the United States (9.8 million cases), and for the vast majority of the cases of undiagnosed diabetes. The risk of type 2 diabetes increases with age, obesity, and physical inactivity. As such, it is often regarded as a disease associated with a modern Western lifestyle. Type 2 diabetes occurs more frequently in women with prior gestational diabetes and in individuals with hypertension and dyslipidemia. Affected patients often have a family history of diabetes. Type 2 diabetes is more common in African Americans, Hispanic Americans, and Native Americans than in non-Hispanic white Americans. Ketoacidosis seldom occurs spontaneously in type 2 diabetes, but it may arise in association with the stress of another illness. Approximately 70 percent of patients with type 2 diabetes are obese.

TREATMENT

Large, prospective, randomized, controlled clinical trials in both type 1 and type 2 diabetes have demonstrated that normal or near-normal blood glucose control can delay or prevent the development of major birth defects and the development and progression of complications affecting the eyes, kidneys, and nerves. Accordingly, the goals for management for both type 1 and type 2 diabetes are to achieve glucose levels as close to the nondiabetic range as possible while minimizing the side-effects of treatment (hypoglycemia and weight gain).

In nondiabetic subjects, blood glucose levels are between 70 and 90 mg/dl (milligrams per deciliter) in the fasting state and rise to 120 to 140 mg/dl one to two hours after meals. These values reflect normal glucose tolerance. Average glucose levels may be assessed by measurement of glycosylated hemoglobin (hemoglobin A1c), is a measure of the average blood glucose level over the previous two to four months. In nondiabetic subjects, hemoglobin A1c is generally less than 6.1 percent, and in poorly controlled diabetic subjects, it may rise to 12 percent or higher.

In general, the goals of treatment are to achieve blood glucose and hemoglobin A1c levels as close to the nondiabetic range as possible with diet, physical activity, and medications.

Diet. In type 1 diabetes, diet is designed to provide adequate nutrients for growth and development and for the maintenance of ideal body weight. The recommended diet includes approximately 20 percent of daily calories from protein, 30 percent from fat, and 50 percent from complex carbohydrates. Simple sugars are limited to prevent excessive glucose excursions, and carbohydrate content is distributed into regular meals and

Table 3

Prevalence of diagnosed diabetes per 1,000 population by age, sex, and race, United States, 1994
Age Group
Population 044 4564 6574 75+ Total
From Centers for Disease Control and Prevention. Diabetes Surveillance, 1997. Atlanta, GA. U.S. Department of Health and Human Services, 1997.
white males 7.8 57.7 96.0 106.8 28.4
black males 10.6 120.8 171.8 120.6 35.9
white females 7.9 51.9 97.2 89.2 30.5
black females 12.1 134.5 171.8 173.5 47.9
Total 8.3 62.2 101.5 103.3 30.8

snacks so that a similar quantity of carbohydrate is consumed at approximately the same time each day.

In type 2 diabetes, caloric content is adjusted to achieve and maintain an ideal body weight or, in those who are obese, to produce gradual weight loss or at least weight maintenance. Dietary composition may also be adjusted in light of intercurrent conditions. For example, sodium may be restricted for patients with hypertension, and both total fat and saturated fat may be restricted for those with high cholesterol.

Exercise. Exercise lowers blood glucose and improves glucose tolerance in diabetics. Other benefits of exercise are reductions in LDL cholesterol and triglycerides levels, and improvements in HDL cholesterol, improvements in blood pressure, improved cardiovascular fitness, and an increased sense of well-being and quality of life. Because exercise may potentiate the hypoglycemic effect of injected insulin and may, paradoxically, result in elevated blood glucose levels and the rapid development of ketosis in type 1 diabetic patients in poor metabolic control, the goal of management in type 1 diabetes is to permit people to enjoy and participate safely in physical and sport activities. In type 2 diabetes, exercise is frequently prescribed as an adjunct to reduced-calorie diets for weight reduction and to improve insulin resistance.

Medications. Because patients with type 1 diabetes are absolutely insulin deficient, treatment requires insulin injections. Although one or two injections per day are often adequate to prevent symptoms of hyperglycemia, intensive therapy employing three or four insulin injections per day, or continuous subcutaneous insulin infusion, may be necessary to achieve near-normal glucose control.

Both oral medications and injected insulin are used for the treatment of type 2 diabetes. Four groups of oral agents are currently available: insulin secretagogues, which enhance nutrient-stimulated insulin secretion; the biguanides, which suppress abnormal glucose production by the liver; the thiazolidinediones, which reduce insulin resistance at the level of muscle and fat; and the alpha-glucosidase inhibitors, which slow the breakdown and absorption of carbohydrates and reduce postprandial glucose excursions. To the extent that these four groups of oral medications have different mechanisms of action, they can be used clinically in combination. When oral agents are ineffective in controlling hyperglycemia or achieving glycemic goals, insulin is added or substituted.

MONITORING

Self-monitoring of blood glucose is integral to modern diabetes therapy. A lancet is used to obtain a small drop of blood, which is placed on a reagent strip and inserted in a small battery-powered meter. The meter reports the blood glucose level in less than a minute. Results of self-monitoring of blood glucose are used to guide adjustments in diet, exercise, and medications, for the monitoring and treatment of hypoglycemia, and in the home management of intercurrent illness.

INCIDENCE AND PREVALENCE

The number of people developing diabetes and the number of people with diabetes are increasing worldwide. In 2000, it was estimated that 154 million persons, or 4.2 percent of the world's population, twenty years of age and older had diabetes. By the year 2025, it is estimated that nearly 300 million persons, or 5.4 percent of the world's population, twenty years of age and older will have diabetes. The major part of this increase will occur in developing countries due to the aging of the population and increasing urbanization (associated with increased body weight and decreased physical activity).

In 1994, there were 939,000 Americans newly diagnosed with diabetes, with a disproportionate number among the elderly and minority populations. The incidence of diagnosed diabetes was3.61 cases per 1,000 persons per year in 1994 (see Table 2).

In 1994, about 8 million persons in the United States (3.1 percent of the population) reported that they had diabetes. The prevalence of diagnosed diabetes increases with age (see Table 3).

MORTALITY

Diabetes is the seventh leading cause of deaths in the United States. The highest death rates due to diabetes are observed in older Americans and in minority populations. Death certificates underestimate diabetes mortality because of underreporting of diabetes. Only about 10 percent of people with diabetes who die have diabetes listed as the underlying cause of death on their death certificates, and only about 40 percent have it listed anywhere on their death certificates. Diabetes was the underlying cause of death for approximately 57,000 Americans in 1994, and diabetes was recorded on the death certificate of approximately 182,000 Americans. In 1994, black women had the highest death rates due to diabetes, followed by white women and men. That same year, 44 percent of all diabetes-related deaths (80,000 deaths) had cardiovascular disease listed as the underlying cause. Of these deaths, approximately 60 percent were caused by ischemic heart disease and 15 percent by stroke.

COMPLICATIONS AND COMORBIDITIES ASSOCIATED WITH DIABETES

Diabetic Ketoacidosis (DKA). Ketoacidosis is an acute metabolic complication of diabetes associated with hyperglycemia, nausea, vomiting, abdominal pain, dehydration, ketonemia, and acidosis. In 1994, DKA was the primary diagnosis for 89,000 hospital discharges and a listed diagnosis for 113,000 hospital discharges. Clinical trials have demonstrated that improved education in self-management and improved access to care can prevent up to 70 percent of DKA hospitalizations.

Adverse Outcomes of Pregnancy. Each year in the United States, type 1 diabetes complicates approximately 7,000 pregnancies and type 2 diabetes complicates approximately 12,000 pregnancies. Up to 1,700 infants (9%) of mothers with pregnancies complicated by diabetes (in the U.S.) are born with birth defects affecting the brain, spinal cord, heart, kidneys, and skeleton. Clinical trials have demonstrated that with intensive glycemic control before conception and during the first trimester, the incidence of major birth defects may be reduced to 2 percent, the rate that occurs in infants of nondiabetic mothers.

Diabetic Eye Disease. Diabetes is the leading cause of new cases of legal blindness in Americans between twenty and seventy-four years of age. As many as 40,000 Americans become blind each year as a result of diabetes. In type 1 diabetes, most legal blindness is due at least in part to diabetic retinopathy. Timely diagnosis and appropriate laser treatment can prevent up to 90 percent of blindness due to diabetic retinopathy. In type 2 diabetes, cataract, glaucoma, and senile macular degeneration are more frequent causes of blindness.

Diabetic Kidney Disease. Diabetic nephropathy is characterized by hypertension, proteinuria, and progressive renal insufficiency. Diabetes is now the leading cause of end-stage renal disease (kidney failure requiring dialysis or kidney transplant for survival). In 1997, over 33,000 Americans developed end-stage renal disease due to diabetes. Early detection, aggressive blood pressure control, and treatment with angiotensin-converting enzyme inhibitors can reduce the progression of diabetic nephropathy by about 60 percent.

Amputations. Diabetic neuropathy, peripheral vascular disease, and infection predispose people with diabetes to gangrene and amputations. More than half of all nontraumatic lower extremity amputations (LEAs) occur in people with diabetes. In 1994, there were approximately 67,000 diabetes-related hospital discharges with LEA reported as a procedure in the United States. Clinical trials have demonstrated that early detection of insensitive and deformed feet and multidisciplinary foot-care programs can reduce the rate of amputation by more than 50 percent.

Cardiovascular Disease Cardiovascular disease (CVD) is the leading cause of morbidity and

Table 4

Incidence of hospital discharge for cardiovascular disease per 1,000 diabetic population by age and sex, United States, 1994
Age Group
Population 044 4564 6574 75+ Total
From Centers for Disease Control and Prevention. Diabetes Surveillance, 1997. Atlanta, GA. U.S. Department of Health and Human Services, 1997.
males 34.3 110.6 228.3 264.9 146.3
females 18.3 101.8 191.3 245.8 139.6
Total 26.1 105.8 207.4 253.0 142.7

mortality in people with diabetes. Stroke, heart attack, and peripheral vascular disease are two to four times more common in people with diabetes than in people without diabetes. In 1994, there were 1,144,000 diabetes-related hospital discharges that had CVD listed as the primary discharge diagnosis (see Table 4). Part of the increased incidence of cardiovascular disease in people with diabetes is due to the greater prevalence of cardiovascular risk factors, including hypertension, dyslipidemia, and cigarette smoking. Clinical trials have demonstrated that pharmacologic treatments for hypertension and dyslipidemia are as effective, if not more effective, in people with diabetes compared to people without diabetes.

COSTS OF DIABETES

Health care costs incurred by people with diabetes include non-diabetes-related and diabetes-related costs. In the United States, in 1992, the direct cost of non-diabetes-related and diabetes-related medical care incurred by people with diabetes was estimated to be $105.2 billion. The direct cost of medical care attributable to diabetes was estimated to be $45.2 billion and the indirect cost of diabetes was estimated to be $46.6 million (see Table 5).

In 1992, per capita health care expenditures for people with diabetes averaged $9,493, compared to $2,604 for people without diabetes. When adjusted for age, per capita health care expenditures for people with diabetes were approximately

Table 5

Costs of diabetes mellitus in the United States, 1992 ($ billion)
Type of Cost Setting Attributable to diabetes* Among People with diabetes**
*From Fox-Ray N, Wills S, Thamer M: Direct and Indirect Costs of Diabetes in the United States in 1992. Alexandria, VA: American Diabetes Association, pp. 1-27, 1993.
**From Rubin RJ, Altman WM, Mendelson DN: Health care expenditures for people with diabetes mellitus, 1992. J Clin Endocrinol Metab 78:809A-809F, 1994.
Direct Hospital 37.2 65.2
Nursing home 1.8
Office 1.1 11.0
Outpatient 2.9 12.5
Emergency room 0.2 1.3
Drugs 1.7 9.9
Home health 0.0 4.0
Dental 1.4
Total 45.2 105.2
Indirect Illness 8.5
Disability 11.2
Death 27.0
Total 46.6

$3,800 higher for people with diabetes than for people without diabetes ($6,425 versus $2,604).

The fact that 62 percent of direct health care costs among people with diabetes and 82 percent of costs directly attributable to diabetes are incurred in the hospital setting suggests that the majority of costs are associated with the treatment of the late, chronic complications of diabetes.

SCREENING FOR TYPE 2 DIABETES

One-third of diabetes in the United States is undiagnosed, and one-third to one-half of all diabetes worldwide is undiagnosed. This finding, combined with the fact that glycemic management can prevent or delay the development of complications, and the fact that diabetic patients may already have complications at clinical diagnosis, have lead some to call for public health screening for type 2 diabetes. In general, screening is appropriate in asymptomatic populations when six specific conditions are met (see Table 6).

Table 6

Characteristics of Diseases that Warrant Diabetes Screening
source: Engelgau, M. M.; Venkat Narayan, K. M.; and Herman, W. H. (2000). "Screening for Type 2 Diabetes." Diabetes Care 23:15631580.
  • The disease represents an important health problem
  • The natural history of the disease is understood
  • The disease has a recognizable preclinical stage during which it may be diagnosed
  • Early treatment confers greater benefit than later treatment
  • Reliable and acceptable tests exist which can detect the preclinical disease
  • The costs of case-finding and treatment are reasonable

Diabetes imposes substantial morbidity and mortality on the population. The natural history of type 2 diabetes is well understood, and with systematic testing, diabetes can be diagnosed in asymptomatic, preclinical, subjects. Unfortunately, although it is clear that intensified management can improve outcomes, no studies have demonstrated the effectiveness or safety of early treatment. Likewise, there is no consensus as to the optimal approach to screening for type 2 diabetes. Ideally, a screening test should be both sensitive and specific. Generally, however, trade-offs must be made between sensitivity and specificity (increasing sensitivity reduces specificity, and increasing specificity reduces sensitivity). In some health systems, the costs of screening and treatment are reasonable, but in others they are simply unaffordable. Finally, although it is recognized that screening must be an ongoing process, no empirical data exist to indicate the optimal screening frequency.

Questionnaires that use self-reported demographic, behavioral, and past medical history to assign a person to a higher or lower risk group; fasting, random, and postprandial urine glucose tests; fasting, random, and postprandial capillary whole blood and capillary plasma glucose tests; fasting, random, and postprandial venous whole blood and plasma glucose tests; and hemoglobin A1c have all been evaluated as screening tests for diabetes. In general, questionnaires perform rather poorly as screening tests for diabetes. Measurement of glycosuria using a cut-off point greater than or equal to a trace value generally has a low sensitivity and a high specificity. Capillary or venous whole blood or plasma glucose determinations have generally performed better than urine glucose testing. With both urine and blood testing, random, postprandial, and glucose-loaded tests perform better than fasting tests. There is little consensus, however, as to optimal cut-points for defining positive tests. Screening with hemoglobin A1c has suffered from lack of standardization of the assay. Even as this problem has been addressed, the test has generally been found to be specific but less sensitive than glucose measurements.

Accordingly, the American Diabetes Association has recommended that clinicians should be vigilant and recognize clinical histories and signs suggestive of diabetes that warrant testing. Generally, screening of high-risk individuals for type 2 diabetes should be performed only as part of ongoing medical care, understanding that the evidence is incomplete and questions remain as to the benefits and risks of early treatment, the optimal screening methods and cut-points, and screening frequency. Community-based screening for diabetes is generally associated with a low yield and poor follow-up, and it probably does not represent a good use of resources.

William H. Herman

Liza L. Ilag

(see also: Cardiovascular Diseases; Glycosylated Hemoglobin; Noncommunicable Disease Control; Nutrition; Screening )

Bibliography

Centers for Disease Control and Prevention (1997). Diabetes Surveillance, 1997. Atlanta, GA: CDC.

DCCT Research Group (1993). "The Effect of Intensive Treatment of Diabetes on the Development and Progression of Long-Term Complications in Insulin-Dependent Diabetes Mellitus." New England Journal of Medicine 329: 977986.

Engelgau, M. M.; Venkat Narayan, K. M.; and Herman, W. H. (2000). "Screening for Type 2 Diabetes." Diabetes Care 23:15631580.

Fox-Ray, N.; Mills, S.; and Thamer, M. (1993). Direct and Indirect Costs of Diabetes in the United States in 1992. Alexandria, VA: American Diabetes Association.

King, H.; Aubert, R. E.; and Herman, W. H. (1998). "Global Burden of Diabetes, 19952025: Prevalence, Numerical Estimates, and Projections." Diabetes Care 21:14141431.

Lebovitz, H. E., ed. (1998) Therapy for Diabetes Mellitus and Related Disorders, 3rd edition. Alexandria, VA: American Diabetes Association.

National Diabetes Data Group (1995). Diabetes in America, 2nd edition. Bethesda, MD: National Institute of Health.

Rubin, R. J.; Altman, W. M.; and Mendelson, D. N. (1994). "Health Care Expenditures for People with Diabetes Mellitus, 1992." Journal of Clinical Endocrinolical Metabolism 78:809a809f.

UK Prospective Diabetes Study (UKPDS) Group (1998). "Intensive Blood-Glucose Control with Sulphonylureas or Insulin Compared with Conventional Treatment and Risk of Complications in Patients with Type 2 Diabetes." Lancet 352:857853. (Published erratum appears in Lancet 354:602.

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Diabetes mellitus

Definition

Diabetes mellitus is a condition in which the pancreas no longer produces enough insulin or when cells stop responding to the insulin that is produced, so that glucose in the blood cannot be absorbed into the cells of the body. Symptoms include frequent urination, tiredness, excessive thirst, and hunger.

Description

Diabetes mellitus is a chronic disease that causes serious health complications including renal (kidney) failure, heart disease, stroke , and blindness. Approximately 14 million Americans (about 5% of the population) have diabetes. Unfortunately, as many as one-half of them are unaware that they have it.

Background

Every cell in the human body needs energy in order to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates (sugars and starches). Glucose from the digested food circulates in the blood as a ready energy source for cells. Insulin is a hormone or chemical produced by cells in the pancreas, an organ located behind the stomach. Insulin binds to receptor sites on the outside of cells and acts like a key to open a door-way

SYMPTOMS OF DIABETES MELLITUS
Excessive thirst
Increased appetite
Increased urination
Weight loss
Fatigue
Nausea
Blurred vision
Frequent vaginal infections in women
Impotence in men
Frequent yeast infections

into the cell through which glucose can enter. Some of the glucose can be converted to concentrated energy sources like glycogen or fatty acids and saved for later use. When there is not enough insulin produced or when the doorway no longer recognizes the insulin key, glucose stays in the blood instead of entering the cells.

The body will attempt to dilute the high level of glucose in the blood, a condition called hyperglycemia, by drawing water out of the cells and into the bloodstream. The excess sugar is excreted in the urine. It is not unusual for people with undiagnosed diabetes to be constantly thirsty, to drink large quantities of water, and to urinate frequently as their bodies try to get rid of the extra glucose. This creates high levels of glucose in the urine.

At the same time that the body is trying to get rid of glucose from the blood, the cells are starving for glucose and sending signals to the body to eat more food, thus making patients extremely hungry. To provide energy for the starving cells, the body also tries to convert fats and proteins to glucose. The breakdown of fats and proteins for energy causes acid compounds called ketones to form in the blood. Ketones also will be excreted in the urine. As ketones build up in the blood, a condition called ketoacidosis can occur. If left untreated, ketoacidosis can lead to coma and death.

Types of diabetes mellitus

Type I diabetes, sometimes called juvenile diabetes, begins most commonly in childhood or adolescence. In this form of diabetes, the body produces little or no insulin. It is characterized by a sudden onset and occurs more frequently in populations descended from northern European countries (Finland, Scotland, Scandinavia)

than in those from southern European countries, the Middle East, or Asia. In the United States, approximately 3 people in 1,000 develop Type I diabetes. This form also is called insulin-dependent diabetes because people who develop this type need to have injections of insulin 12 times per day.

Brittle diabetics are a subgroup of Type I where patients have frequent and rapid swings of blood sugar levels between hyperglycemia (a condition where there is too much glucose or sugar in the blood) and hypoglycemia (a condition where there are abnormally low levels of glucose or sugar in the blood). These patients may require several injections of different types of insulin or an insulin pump during the day to keep their blood sugar within a fairly normal range.

The more common form of diabetes, Type II, occurs in approximately 35% of Americans under 50 years of age, and increases to 1015% in those over 50. More than 90% of the diabetics in the United States are Type II diabetics. In 2003, a report noted that nearly one-third of the U.S. population over age 20 has this form of diabetes but remains undiagnosed. Sometimes called age-onset or adult-onset diabetes, this form of diabetes occurs most often in people who are overweight and do not exercise . It also is more common in people of Native American, Hispanic, and African-American descent. People who have migrated to Western cultures from East India, Japan, and Australian Aboriginal cultures are also more likely to develop Type II diabetes than those who remain in their original countries.

Type II is considered a milder form of diabetes because of its slow onset (sometimes developing over the course of several years) and because it can usually be controlled with diet and oral medication. The consequences of uncontrolled and untreated Type II diabetes, however, are just as serious as those for Type I. This form also is called noninsulin-dependent diabetes, a term that is somewhat misleading. Many people with Type II diabetes can control the condition with diet and oral medications, however, insulin injections sometimes are necessary.

Another form of diabetes, called gestational diabetes, can develop during pregnancy and generally resolves after the baby is delivered. This diabetic condition develops during the second or third trimester of pregnancy in about 2% of pregnancies. The condition usually is treated by diet, however, insulin injections may be required. Women who have diabetes during pregnancy are at higher risk for developing Type II diabetes within 510 years.

Diabetes also can develop as a result of pancreatic disease, alcoholism , malnutrition, or other severe illnesses that stress the body.

Causes & symptoms

The causes of diabetes mellitus are unclear, however, there seem to be both hereditary (genetic factors passed on in families) and environmental factors involved. Research has shown that some people who develop diabetes have common genetic markers. In Type I diabetes, an autoimmune response is believed to be triggered by a virus or another microorganism that destroys the cells that produce insulin. In Type II diabetes, age, obesity , and family history of diabetes play a role.

In Type II diabetes, the pancreas may produce enough insulin, however, cells have become resistant to the insulin produced and it may not work as effectively. Symptoms of Type II diabetes can begin so gradually that a person may not know that he or she has it. Early signs are tiredness, extreme thirst, and frequent urination. Other symptoms may include sudden weight loss, slow wound healing, urinary tract infections, gum disease , or blurred vision. It is not unusual for Type II diabetes to be detected while a patient is seeing a doctor about a health concern that was caused by the yet undiagnosed diabetes.

Individuals who are at high risk of developing Type II diabetes mellitus include people who:

  • are obese (more than 20% above their ideal body weight)
  • have a relative with diabetes mellitus
  • belong to a high-risk ethnic population (African-American, Native American, Hispanic, or Native Hawaiian)
  • have been diagnosed with gestational diabetes or have delivered a baby weighing more than 9 lb (4 kg)
  • have high blood pressure (140/90 mmHg or above)
  • have a high density lipoprotein cholesterol level less than or equal to 35 mg/dL and/or a triglyceride level greater than or equal to 250 mg/dL
  • have had impaired glucose tolerance or impaired fasting glucose on previous testing

Several common medications can impair the body's use of insulin, causing a condition known as secondary diabetes. These medications include treatments for high blood pressure (furosemide, clonidine, and thiazide diuretics), drugs with hormonal activity (oral contraceptives, thyroid hormone, progestins, and glucocorticorids), and the anti-inflammation drug indomethacin. Several drugs that are used to treat mood disorders (such as anxiety and depression ) also can impair glucose absorption. These drugs include haloperidol, lithium carbonate, phenothiazines, tricyclic antidepressants, and adrenergic agonists. Other medications that can cause diabetes symptoms include isoniazid, nicotinic acid, cimetidine, and heparin.

Symptoms of diabetes can develop suddenly (over days or weeks) in previously healthy children or adolescents, or can develop gradually (over several years) in overweight adults over the age of 40. The classic symptoms include feeling tired and sick, frequent urination, excessive thirst, excessive hunger, and weight loss.

Ketoacidosis, a condition due to starvation or un-controlled diabetes, is common in Type I diabetes. Ketones are acid compounds that form in the blood when the body breaks down fats and proteins. Symptoms include abdominal pain, vomiting , rapid breathing, extreme tiredness, and drowsiness. Patients with ketoacidosis will also have a sweet breath odor. Left untreated, this condition can lead to coma and death.

With Type II diabetes, the condition may not become evident until the patient presents for medical treatment for some other condition. A patient may have heart disease, chronic infections of the gums and urinary tract, blurred vision, numbness in the feet and legs, or slow-healing wounds . Women may experience genital itching .

Diagnosis

Diabetes is suspected based on symptoms. Urine tests and blood tests can be used to confirm a diagnosis of diabetes based on the amount of glucose in the urine and blood. Urine tests also can detect ketones and protein in the urine which may help diagnose diabetes and assess how well the kidneys are functioning. These tests also can be used to monitor the disease once the patient is under treatment.

Urine tests

Clinistix and Diastix are paper strips or dipsticks that change color when dipped in urine. The test strip is compared to a chart that shows the amount of glucose in the urine based on the change in color. The level of glucose in the urine lags behind the level of glucose in the blood. Testing the urine with a test stick, paper strip, or tablet is not as accurate as blood testing, however it can give a fast and simple reading.

Ketones in the urine can be detected using similar types of dipstick tests (Acetest or Ketostix). Ketoacidosis can be a life-threatening situation in Type I diabetics, so having a quick and simple test to detect ketones can assist in establishing a diagnosis sooner.

Another dipstick test can determine the presence of protein or albumin in the urine. Protein in the urine can indicate problems with kidney function and can be used to track the development of renal failure. A more sensitive test for urine protein uses radioactively tagged chemicals to detect microalbuminuria, small amounts of protein in the urine, which may not show up on dipstick tests.

Blood tests

Fasting glucose test. Blood is drawn from a vein in the patient's arm after the patient has not eaten for at least eight hours, usually in the morning before breakfast. The red blood cells are separated from the sample and the amount of glucose is measured in the remaining plasma. A plasma level of 7.8 mmol/L (200 mg/L) or greater can indicate diabetes. The fasting glucose test is usually repeated on another day to confirm the results.

Postprandial glucose test. Blood is taken right after the patient has eaten a meal.

Oral glucose tolerance test. Blood samples are taken from a vein before and after a patient drinks a sweet syrup of glucose and other sugars. In a non-diabetic, the level of glucose in the blood goes up immediately after the drink and then decreases gradually as insulin is used by the body to metabolize, or absorb, the sugar. In a diabetic, the glucose in the blood goes up and stays high after drinking the sweetened liquid. A plasma glucose level of 11.1 mmol/L (200 mg/dL) or higher at two hours after drinking the syrup and at one other point during the two-hour test period confirms the diagnosis of diabetes.

A diagnosis of diabetes is confirmed if a plasma glucose level of at least 11.1 mmol/L, a fasting plasma glucose level of at least 7 mmol/L; or a two-hour plasma glucose level of at least 11.1 mmol/L during an oral glucose tolerance test.

In 2002, scientists announced that a new simple blood test to screen for diabetes had been developed. Prior to that time, community-wide screening procedures had not proven cost-effective. The new screening test proved cost-effective if conducted in physician offices on patients with three known risk factors of obesity, self-reported high blood pressure, and family history of diabetes.

Home blood glucose monitoring kits are available so diabetics can monitor their own levels. A small needle or lancet is used to prick the finger and a drop of blood is collected and analyzed by a monitoring device. Some patients may test their blood glucose levels several times during a day and use this information to adjust their diet or doses of insulin.

Treatment

There is currently no cure for diabetes. Diet, exercise, and careful monitoring of blood glucose levels are the keys to manage diabetes so that patients can live a relatively normal life. Diabetes can be life-threatening if not properly managed, so patients should not attempt to treat this condition without medical supervision. Treatment of diabetes focuses on two goals: keeping blood glucose within normal range and preventing the development of long-term complications. Alternative treatments cannot replace the need for insulin but they may enhance insulin's effectiveness and may lower blood glucose levels. In addition, alternative medicines may help to treat complications of the disease and improve quality of life.

Diet

Diet and moderate exercise are the first treatments implemented in diabetes. For many Type II diabetics, weight loss may be an important goal to help them to control their diabetes. A well-balanced, nutritious diet provides approximately 5060% of calories from carbohydrates, approximately 1020% of calories from protein, and less than 30% of calories from fat. The number of calories required depends on the patient's age, weight, and activity level. The calorie intake also needs to be distributed over the course of the entire day so surges of glucose entering the blood system are kept to a minimum. In 2002, a Korean study demonstrated that eating a combination of whole grains and legume powder was beneficial in lowering blood glucose levels in men with diabetes.

Keeping track of the number of calories provided by different foods can be complicated, so patients are usually advised to consult a nutritionist or dietitian. An individualized, easy-to-manage diet plan can be set up for each patient. Both the American Diabetes Association and the American Dietetic Association recommend diets based on the use of food exchange lists. Each food exchange contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient's diet plan will consist of a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at meal times and as snacks. Patients have flexibility in choosing the foods they eat as long as they don't exceed the number of exchanges prescribed. The food exchange system, along with a plan of moderate exercise, can help diabetics lose excess weight and improve their overall health. Certain foods will be emphasized over others to promote a healthy heart as well.

Supplements

CHROMIUM PICOLINATE. Several studies have had conflicting results on the effectiveness of chromium picolinate supplementation for control of blood glucose levels. In one study, approximately 70% of the diabetics receiving 200 micrograms of chromium picolinate daily reduced their need for insulin and medications. While some studies have shown that supplementation caused significant weight loss, and decreases in blood glucose and serum triglycerides, others have shown no benefit. Chromium supplementation may cause hypoglycemia and other side effects.

MAGNESIUM. Magnesium deficiency may interfere with insulin secretion and uptake and worsen the patient's control of blood sugar. Also, magnesium deficiency puts diabetics at risk for certain complications, especially retinopathy and cardiovascular disease.

VANADIUM. Vanadium has been shown to bring blood glucose to normal levels in diabetic animals. Also, people who took vanadium were able to decrease their need for insulin.

Chinese medicine

Non-insulin dependent diabetics who practiced daily qigong for one year had decreases in fasting blood glucose and blood insulin levels. Acupuncture may relieve pain in patients with diabetic neuropathy. Acupuncture also may help to bring blood glucose to normal levels in diabetics who do not require insulin.

Best when used in consultation with a Chinese medicine physician, some Chinese patent medicines that alleviate symptoms of or complications from diabetes include:

  • Xiao Ke Wan (Emaciation and Thirst Pill) for diabetics with increased levels of sugar in blood and urine.
  • Yu Quan Wan (Jade Spring Pill) for diabetics with a deficiency of Yin.
  • Liu Wei Di Huang Wan (Six Ingredient Pill with Rehmannia) for stabilized diabetics with a deficiency of Kidney Yin.
  • Jin Gui Shen Wan (Kidney Qi Pill) for stabilized diabetics with a deficiency of Kidney Yang.

Herbals

Herbal medicine can have a positive effect on blood glucose and quality of life in diabetics. The results of clinical study of various herbals are:

  • Wormwood (Artemisia herba-alba ) decreased blood glucose.
  • Gurmar (Gymnema sylvestre ) decreased blood glucose levels and the need for insulin.
  • Coccinia indica improved glucose tolerance.
  • Fenugreek seed powder (Trigonella foenum graecum ) decreased blood glucose and improved glucose tolerance.
  • Bitter melon (Momordica charantia ) decreased blood glucose and improved glucose tolerance.
  • Cayenne pepper (Capsicum frutescens ) can help relieve pain in the peripheral nerves (a type of diabetic neuropathy).

Other herbals that may treat or prevent diabetes and its complications include:

  • Bilberry (Vaccinium myrtillus ) may lower blood glucose levels and maintain healthy blood vessels.
  • Garlic (Allium sativum ) may lower blood sugar and cholesterol levels.
  • Onions (Allium cepa ) may help lower blood glucose levels.
  • Ginkgo (Ginkgo biloba ) improves blood circulation.

Yoga

Studies of diabetics have shown that practicing yoga leads to decreases in blood glucose, increased glucose tolerance, decreased need for diabetes medications, and improved insulin processes. Yoga also enhances the sense of well-being.

Biofeedback

Many studies have been performed to test the benefit of adding biofeedback to the diabetic's treatment plan. Relaxation techniques, such as visualization, usually were included. Biofeedback can have significant effects on diabetes including improved glucose tolerance and decreased blood glucose levels. In addition, biofeedback can be used to treat diabetic complications and improve quality of life.

Allopathic treatment

Traditional treatment of diabetes begins with a well balanced diet and moderate exercise. Medications are prescribed only if the patient's blood glucose cannot be controlled by these methods.

Oral medications

Oral medications are available to lower blood glucose in Type II diabetics. Drugs first prescribed for Type II diabetes are in a class of compounds called sulfonylureas and include tolbutamide, tolazamide, acetohexamide, chlorpropamide, glyburide, glimeperide, and glipizide. The way that these drugs work is not well understood, however, they seem to stimulate cells of the pancreas to produce more insulin. New medications that are available to treat diabetes include metformin, acarbose, and troglitizone. These medications are not a substitute for a well planned diet and moderate exercise. Oral medications are not effective for Type I diabetes, in which the patient produces little or no insulin.

Insulin

Patients with Type I diabetes need daily injections of insulin to help their bodies use glucose. Some patients with Type II diabetes may need to use insulin injections if their diabetes cannot be controlled. Injections are given subcutaneouslyjust under the skin, using a small needle and syringe. Purified human insulin is most commonly used, however, insulin from beef and pork sources also is available. Insulin may be given as an injection of a single dose of one type of insulin once a day. Different types of insulin can be mixed and given in one dose or split into two or more doses during a day. Patients who require multiple injections over the course of a day may be able to use an insulin pump that administers small doses of insulin on demand. In 2002, reports announced that early research shows a synthetic insulin called insulin glargine might show promise for patients at risk for hypoglycemia from insulin therapy. Clinical trials showed that when used in combination with certain other short-acting insulins, it safely regulated blood glucose for longer durations and was well tolerated by patients.

Hypoglycemia, or low blood sugar, can be caused by too much insulin, too little food (or eating too late to coincide with the action of the insulin), alcohol consumption, or increased exercise. A patient with symptoms of hypoglycemia may be hungry, sweaty, shaky, cranky, confused, and tired. Left untreated, the patient can lose consciousness or have a seizure. This condition is sometimes called an insulin reaction and should be treated by giving the patient something sweet to eat or drink like candy, sugar cubes, or juice.

Surgery

Transplantation of a healthy pancreas into a diabetic patient is a successful treatment, however, this transplant usually is done only if a kidney transplant is performed at the same time. It is not clear if the potential benefits of transplantation outweigh the risks of the surgery and subsequent drug therapy.

Expected results

Uncontrolled diabetes is a leading cause of blindness, end-stage renal disease, and limb amputations. It also doubles the risk of heart disease and increases the risk of stroke. Eye problems including cataracts, glaucoma , and retinopathy also are more common in diabetics. Kidney disease is a common complication of diabetes and may require kidney dialysis or a kidney transplant. Babies born to diabetic mothers have an increased risk of birth defects and distress at birth.

Diabetic peripheral neuropathy is a condition where nerve endings, particularly in the legs and feet, become less sensitive. Diabetic foot ulcers are a problem since the patient does not feel the pain of a blister, callous, or other minor injury. Poor blood circulation in the legs and feet contributes to delayed wound healing. The inability to sense pain along with the complications of delayed wound healing can result in minor injuries, blisters , or callouses becoming infected and difficult to treat. Severely infected tissue breaks down and rots, often necessitating amputation of toes, feet, or legs.

Prevention

Research continues on ways to prevent diabetes and to detect those at risk for developing diabetes. While the onset of Type I diabetes is unpredictable, the risk of developing Type II diabetes can be reduced by maintaining ideal weight and exercising regularly. The physical and emotional stress of surgery, illness, and alcoholism can increase the risks of diabetes, so maintaining a healthy lifestyle is critical to preventing the onset of Type II diabetes and preventing further complications of the disease.

In early 2002, researchers announced that patients at high risk for developing diabetes who took an ACE inhibitor called ramipril reduced their risk of developing diabetes substantially. Another report at Duke University showed that sustained intensive exercise could forestall development of diabetes or cardiovascular disease in high-risk patients. The benefits of long-term exercise even continue one month after exercising stops. In 2003, advances in genetics found a key gene that may explain why some people are more susceptible to the disease than others.

Resources

BOOKS

Foster, Daniel W. "Diabetes Mellitus." In Harrison's Principles of Internal Medicine. 14th ed. Edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998.

Garber, Alan J. "Diabetes Mellitus." In Internal Medicine. Edited by Jay H. Stein, et al. St. Louis: Mosby, 1998.

Karam, John H. "Diabetes Mellitus & Hypoglycemia." In Current Medical Diagnosis & Treatment 1998. 37th ed. Edited by L.M. Tierney, Jr., S.J. McPhee, and M.A. Papadakis. Stamford, CT: Appleton & Lange, 1998.

McGrady, Angele and James Horner. "Complementary/Alternative Therapies in General Medicine: Diabetes Mellitus." In Complementary/Alternative Medicine: An Evidence Based Approach. Edited by John W. Spencer and Joseph J. Jacobs. St. Louis: Mosby, 1999.

Sherwin, Robert S. "Diabetes Mellitus." In Cecil Textbook of Medicine. 20th ed. Edited by J. Claude Bennett and Fred Plum. Philadelphia, PA: W.B. Saunders Company, 1996.

Smit, Charles Kent, John P. Sheehan, and Margaret M. Ulchaker. "Diabetes Mellitus." In Family Medicine, Principles and Practice. 5th ed. Edited by Robert B. Taylor. New York: Springer-Verlag, 1998.

Ying, Zhou Zhong and Jin Hui De. "Endocrinology." In Clinical Manual of Chinese Herbal Medicine and Acupuncture. New York: Churchill Livingston, 1997.

PERIODICALS

"Exercise Can Forestall Diabetes in At-Risk Patients." Diabetes Week (March 25, 2002):2.

Fox, Gary N., and Zijad Sabovic. "Chromium Picolinate Supplementation for Diabetes Mellitus." The Journal of Family Practice 46 (1998): 83-86.

Hartnett, Terry."Early Results Show Promise for Synthetic Insulin." Diabetes Week (March 18, 2002):4.

Jenkins, David JA, et al."Type 2 Diabetes and the Vegetarian Diet." American Journal of Clinical Nutrition (September 2003):610S.

"Mouse, Stripped of a Key Gene, Resists Diabetes." Biotech Week (September 24, 2003):557.

"Nearly One-third of Diabetes Undiganosed, According to New Government Data." Medical Letter on the CDC & FDA (September 28, 2003):13.

"Ramipril Cuts Diabetes Risk." Family Practice News 32, no. 3 (February 1, 2002):10.

"Simple Blood Test Could Detect New Cases of Diabetes." Diabetes Week (January 21, 2002):4.

"Whole Grain and Legume Powder Diet Benefits Diabetics and the Healthy." Diabetes Week (January 7, 2002):8.

"Trends in the Prevalence and Incidence of Self-Reported Diabetes Mellitus-United States, 1980-1994." Morbidity & Mortality Weekly Report 46 (1997): 1014-1018.

"Updated Guidelines for the Diagnosis of Diabetes in the US." Drugs & Therapy Perspectives 10 (1997): 12-13.

ORGANIZATIONS

American Diabetes Association. 1660 Duke Street, Alexandria, VA 22314. (703) 549-1500. Diabetes Information and Action Line: (800) DIABETES. http://www.diabetes.org.

American Dietetic Association. 430 North Michigan Avenue, Chicago, IL 60611. (312) 822-0330. http://www.eatright.org.

Juvenile Diabetes Foundation International. 120 Wall Street, New York, NY 10005-4001. (212) 785-9595. (800) JDF-CURE.

National Diabetes Information Clearinghouse. 1 Information Way, Bethesda, MD 20892-3560. (301) 654-3327.

National Institutes of Health. National Institute of Diabetes, Digestive and Kidney Diseases. 9000 Rockville Pike, Bethesda, MD 20892. (301) 496-3583. http://www.niddk.nih.gov.

OTHER

Centers for Disease Control and Prevention Diabetes. http://www.cdc.gov/nccdphp/ddt/ddthome.htm.

"Insulin-Dependent Diabetes." National Institute of Diabetes and Digestive and Kidney Diseases. National Institutes of Health, NIH Publication No. 94-2098.

"Noninsulin-Dependent Diabetes." National Institute of Diabetes and Digestive and Kidney Diseases. National Institutes of Health, NIH Publication No. 92-241.

Belinda Rowland

Teresa G. Odle

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Diabetes Mellitus

Definition

Diabetes mellitus is a condition in which the pancreas no longer produces enough insulin or cells stop responding to the insulin that is produced, so that glucose in the blood cannot be absorbed into the cells of the body. Symptoms include frequent urination, lethargy, excessive thirst, and hunger. The treatment includes changes in diet, oral medications, and in some cases, daily injections of insulin.

Description

Diabetes mellitus is a chronic disease that causes serious health complications including renal (kidney) failure, heart disease, stroke, and blindness. Approximately 17 million Americans have diabetes. Unfortunately, as many as one-half are unaware they have it.

Background

Every cell in the human body needs energy in order to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates (sugars and starches). Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. Insulin is a hormone or chemical produced by cells in the pancreas, an organ located behind the stomach. Insulin bonds to a receptor site on the outside of cell and acts like a key to open a doorway into the cell through which glucose can enter. Some of the glucose can be converted to concentrated energy sources like glycogen or fatty acids and saved for later use. When there is not enough insulin produced or when the doorway no longer recognizes the insulin key, glucose stays in the blood rather entering the cells.

The body will attempt to dilute the high level of glucose in the blood, a condition called hyperglycemia, by drawing water out of the cells and into the bloodstream in an effort to dilute the sugar and excrete it in the urine. It is not unusual for people with undiagnosed diabetes to be constantly thirsty, drink large quantities of water, and urinate frequently as their bodies try to get rid of the extra glucose. This creates high levels of glucose in the urine.

At the same time that the body is trying to get rid of glucose from the blood, the cells are starving for glucose and sending signals to the body to eat more food, thus making patients extremely hungry. To provide energy for the starving cells, the body also tries to convert fats and proteins to glucose. The breakdown of fats and proteins for energy causes acid compounds called ketones to form in the blood. Ketones also will be excreted in the urine. As ketones build up in the blood, a condition called ketoacidosis can occur. This condition can be life threatening if left untreated, leading to coma and death.

Types of diabetes mellitus

Type I diabetes, sometimes called juvenile diabetes, begins most commonly in childhood or adolescence. In this form of diabetes, the body produces little or no insulin. It is characterized by a sudden onset and occurs more frequently in populations descended from Northern European countries (Finland, Scotland, Scandinavia) than in those from Southern European countries, the Middle East, or Asia. In the United States, approximately three people in 1,000 develop Type I diabetes. This form also is called insulin-dependent diabetes because people who develop this type need to have daily injections of insulin.

Brittle diabetics are a subgroup of Type I where patients have frequent and rapid swings of blood sugar levels between hyperglycemia (a condition where there is too much glucose or sugar in the blood) and hypoglycemia (a condition where there are abnormally low levels of glucose or sugar in the blood). These patients may require several injections of different types of insulin during the day to keep the blood sugar level within a fairly normal range.

The more common form of diabetes, Type II, occurs in approximately 3-5% of Americans under 50 years of age, and increases to 10-15% in those over 50. More than 90% of the diabetics in the United States are Type II diabetics. Sometimes called age-onset or adult-onset diabetes, this form of diabetes occurs most often in people who are overweight and who do not exercise. It is also more common in people of Native American, Hispanic, and African-American descent. People who have migrated to Western cultures from East India, Japan, and Australian Aboriginal cultures also are more likely to develop Type II diabetes than those who remain in their original countries.

Type II is considered a milder form of diabetes because of its slow onset (sometimes developing over the course of several years) and because it usually can be controlled with diet and oral medication. The consequences of uncontrolled and untreated Type II diabetes, however, are the just as serious as those for Type I. This form is also called noninsulin-dependent diabetes, a term that is somewhat misleading. Many people with Type II diabetes can control the condition with diet and oral medications, however, insulin injections are sometimes necessary if treatment with diet and oral medication is not working.

Another form of diabetes called gestational diabetes can develop during pregnancy and generally resolves after the baby is delivered. This diabetic condition develops during the second or third trimester of pregnancy in about 2% of pregnancies. In 2004, incidence of gestational diabetes were reported to have increased 35% in 10 years. Children of women with gestational diabetes are more likely to be born prematurely, have hypoglycemia, or have severe jaundice at birth. The condition usually is treated by diet, however, insulin injections may be required. These women who have diabetes during pregnancy are at higher risk for developing Type II diabetes within 5-10 years.

Diabetes also can develop as a result of pancreatic disease, alcoholism, malnutrition, or other severe illnesses that stress the body.

Causes and symptoms

Causes

The causes of diabetes mellitus are unclear, however, there seem to be both hereditary (genetic factors passed on in families) and environmental factors involved. Research has shown that some people who develop diabetes have common genetic markers. In Type I diabetes, the immune system, the body's defense system against infection, is believed to be triggered by a virus or another microorganism that destroys cells in the pancreas that produce insulin. In Type II diabetes, age, obesity, and family history of diabetes play a role.

In Type II diabetes, the pancreas may produce enough insulin, however, cells have become resistant to the insulin produced and it may not work as effectively. Symptoms of Type II diabetes can begin so gradually that a person may not know that he or she has it. Early signs are lethargy, extreme thirst, and frequent urination. Other symptoms may include sudden weight loss, slow wound healing, urinary tract infections, gum disease, or blurred vision. It is not unusual for Type II diabetes to be detected while a patient is seeing a doctor about another health concern that is actually being caused by the yet undiagnosed diabetes.

Individuals who are at high risk of developing Type II diabetes mellitus include people who:

  • are obese (more than 20% above their ideal body weight)
  • have a relative with diabetes mellitus
  • belong to a high-risk ethnic population (African-American, Native American, Hispanic, or Native Hawaiian)
  • have been diagnosed with gestational diabetes or have delivered a baby weighing more than 9 lbs (4 kg)
  • have high blood pressure (140/90 mmHg or above)
  • have a high density lipoprotein cholesterol level less than or equal to 35 mg/dL and/or a triglyceride level greater than or equal to 250 mg/dL
  • have had impaired glucose tolerance or impaired fasting glucose on previous testing

Several common medications can impair the body's use of insulin, causing a condition known as secondary diabetes. These medications include treatments for high blood pressure (furosemide, clonidine, and thiazide diuretics ), drugs with hormonal activity (oral contraceptives, thyroid hormone, progestins, and glucocorticorids), and the anti-inflammation drug indomethacin. Several drugs that are used to treat mood disorders (such as anxiety and depression) also can impair glucose absorption. These drugs include haloperidol, lithium carbonate, phenothiazines, tricyclic antidepressants, and adrenergic agonists. Other medications that can cause diabetes symptoms include isoniazid, nicotinic acid, cimetidine, and heparin. A 2004 study found that low levels of the essential mineral chromium in the body may be linked to increased risk for diseases associated with insulin resistance.

Symptoms

Symptoms of diabetes can develop suddenly (over days or weeks) in previously healthy children or adolescents, or can develop gradually (over several years) in overweight adults over the age of 40. The classic symptoms include feeling tired and sick, frequent urination, excessive thirst, excessive hunger, and weight loss.

Ketoacidosis, a condition due to starvation or uncontrolled diabetes, is common in Type I diabetes. Ketones are acid compounds that form in the blood when the body breaks down fats and proteins. Symptoms include abdominal pain, vomiting, rapid breathing, extreme lethargy, and drowsiness. Patients with ketoacidosis will also have a sweet breath odor. Left untreated, this condition can lead to coma and death.

With Type II diabetes, the condition may not become evident until the patient presents for medical treatment for some other condition. A patient may have heart disease, chronic infections of the gums and urinary tract, blurred vision, numbness in the feet and legs, or slow-healing wounds. Women may experience genital itching.

Diagnosis

Diabetes is suspected based on symptoms. Urine tests and blood tests can be used to confirm a diagnose of diabetes based on the amount of glucose found. Urine can also detect ketones and protein in the urine that may help diagnose diabetes and assess how well the kidneys are functioning. These tests also can be used to monitor the disease once the patient is on a standardized diet, oral medications, or insulin.

Urine tests

Clinistix and Diastix are paper strips or dipsticks that change color when dipped in urine. The test strip is compared to a chart that shows the amount of glucose in the urine based on the change in color. The level of glucose in the urine lags behind the level of glucose in the blood. Testing the urine with a test stick, paper strip, or tablet that changes color when sugar is present is not as accurate as blood testing, however it can give a fast and simple reading.

Ketones in the urine can be detected using similar types of dipstick tests (Acetest or Ketostix). Ketoacidosis can be a life-threatening situation in Type I diabetics, so having a quick and simple test to detect ketones can assist in establishing a diagnosis sooner.

Another dipstick test can determine the presence of protein or albumin in the urine. Protein in the urine can indicate problems with kidney function and can be used to track the development of renal failure. A more sensitive test for urine protein uses radioactively tagged chemicals to detect microalbuminuria, small amounts of protein in the urine, that may not show up on dipstick tests.

Blood tests

FASTING GLUCOSE TEST. Blood is drawn from a vein in the patient's arm after a period at least eight hours when the patient has not eaten, usually in the morning before breakfast. The red blood cells are separated from the sample and the amount of glucose is measured in the remaining plasma. A plasma level of 7.8 mmol/L (200 mg/L) or greater can indicate diabetes. The fasting glucose test is usually repeated on another day to confirm the results.

POSTPRANDIAL GLUCOSE TEST. Blood is taken right after the patient has eaten a meal.

ORAL GLUCOSE TOLERANCE TEST. Blood samples are taken from a vein before and after a patient drinks a thick, sweet syrup of glucose and other sugars. In a non-diabetic, the level of glucose in the blood goes up immediately after the drink and then decreases gradually as insulin is used by the body to metabolize, or absorb, the sugar. In a diabetic, the glucose in the blood goes up and stays high after drinking the sweetened liquid. A plasma glucose level of 11.1 mmol/L (200 mg/dL) or higher at two hours after drinking the syrup and at one other point during the two-hour test period confirms the diagnosis of diabetes.

A diagnosis of diabetes is confirmed if there are symptoms of diabetes and a plasma glucose level of at least 11.1 mmol/L, a fasting plasma glucose level of at least 7 mmol/L; or a two-hour plasma glucose level of at least 11.1 mmol/L during an oral glucose tolerance test.

Home blood glucose monitoring kits are available so patients with diabetes can monitor their own levels. A small needle or lancet is used to prick the finger and a drop of blood is collected and analyzed by a monitoring device. Some patients may test their blood glucose levels several times during a day and use this information to adjust their doses of insulin.

Treatment

There is currently no cure for diabetes. The condition, however, can be managed so that patients can live a relatively normal life. Treatment of diabetes focuses on two goals: keeping blood glucose within normal range and preventing the development of long-term complications. Careful monitoring of diet, exercise, and blood glucose levels are as important as the use of insulin or oral medications in preventing complications of diabetes. In 2003, the American Diabetes Association updated its Standards of Care for the management of diabetes. These standards help manage health care providers in the most recent recommendations for diagnosis and treatment of the disease.

Dietary changes

Diet and moderate exercise are the first treatments implemented in diabetes. For many Type II diabetics, weight loss may be an important goal in helping them to control their diabetes. A well-balanced, nutritious diet provides approximately 50-60% of calories from carbohydrates, approximately 10-20% of calories from protein, and less than 30% of calories from fat. The number of calories required by an individual depends on age, weight, and activity level. The calorie intake also needs to be distributed over the course of the entire day so surges of glucose entering the blood system are kept to a minimum.

Keeping track of the number of calories provided by different foods can become complicated, so patients usually are advised to consult a nutritionist or dietitian. An individualized, easy to manage diet plan can be set up for each patient. Both the American Diabetes Association and the American Dietetic Association recommend diets based on the use of food exchange lists. Each food exchange contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient's diet plan will consist of a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at meal times and as snacks. Patients have flexibility in choosing which foods they eat as long as they stick with the number of exchanges prescribed.

For many Type II diabetics, weight loss is an important factor in controlling their condition. The food exchange system, along with a plan of moderate exercise, can help them lose excess weight and improve their overall health.

Oral medications

Oral medications are available to lower blood glucose in Type II diabetics. In 1990, 23.4 outpatient prescriptions for oral antidiabetic agents were dispensed. By 2001, the number had increased to 91.8 million prescriptions. Oral antidiabetic agents accounted for more than $5 billion dollars in worldwide retail sales per year in the early twenty-first century and were the fastest-growing segment of diabetes drugs. The drugs first prescribed for Type II diabetes are in a class of compounds called sulfonylureas and include tolbutamide, tolazamide, acetohexamide, and chlorpropamide. Newer drugs in the same class are now available and include glyburide, glimeperide, and glipizide. How these drugs work is not well understood, however, they seem to stimulate cells of the pancreas to produce more insulin. New medications that are available to treat diabetes include metformin, acarbose, and troglitizone. The choice of medication depends in part on the individual patient profile. All drugs have side effects that may make them inappropriate for particular patients. Some for example, may stimulate weight gain or cause stomach irritation, so they may not be the best treatment for someone who is already overweight or who has stomach ulcers. Others, like metformin, have been shown to have positive effects such as reduced cardiovascular mortality, but but increased risk in other situations. While these medications are an important aspect of treatment for Type II diabetes, they are not a substitute for a well planned diet and moderate exercise. Oral medications have not been shown effective for Type I diabetes, in which the patient produces little or no insulin.

Constant advances are being made in development of new oral medications for persons with diabetes. In 2003, a drug called Metaglip combining glipizide and metformin was approved in a dingle tablet. Along with diet and exercise, the drug was used as initial therapy for Type 2 diabetes. Another drug approved by the U.S. Food and Drug Administration (FDA) combines metformin and rosiglitazone (Avandia), a medication that increases muscle cells' sensitivity to insulin. It is marketed under the name Avandamet. So many new drugs are under development that it is best to stay in touch with a physician for the latest information; physicians can find the best drug, diet and exercise program to fit an individual patient's need.

Insulin

Patients with Type I diabetes need daily injections of insulin to help their bodies use glucose. The amount and type of insulin required depends on the height, weight, age, food intake, and activity level of the individual diabetic patient. Some patients with Type II diabetes may need to use insulin injections if their diabetes cannot be controlled with diet, exercise, and oral medication. Injections are given subcutaneously, that is, just under the skin, using a small needle and syringe. Injection sites can be anywhere on the body where there is looser skin, including the upper arm, abdomen, or upper thigh.

Purified human insulin is most commonly used, however, insulin from beef and pork sources also are available. Insulin may be given as an injection of a single dose of one type of insulin once a day. Different types of insulin can be mixed and given in one dose or split into two or more doses during a day. Patients who require multiple injections over the course of a day may be able to use an insulin pump that administers small doses of insulin on demand. The small battery-operated pump is worn outside the body and is connected to a needle that is inserted into the abdomen. Pumps can be programmed to inject small doses of insulin at various times during the day, or the patient may be able to adjust the insulin doses to coincide with meals and exercise.

Regular insulin is fast-acting and starts to work within 15-30 minutes, with its peak glucose-lowering effect about two hours after it is injected. Its effects last for about four to six hours. NPH (neutral protamine Hagedorn) and Lente insulin are intermediate-acting, starting to work within one to three hours and lasting up to 18-26 hours. Ultra-lente is a long-acting form of insulin that starts to work within four to eight hours and lasts 28-36 hours.

Hypoglycemia, or low blood sugar, can be caused by too much insulin, too little food (or eating too late to coincide with the action of the insulin), alcohol consumption, or increased exercise. A patient with symptoms of hypoglycemia may be hungry, cranky, confused, and tired. The patient may become sweaty and shaky. Left untreated, the patient can lose consciousness or have a seizure. This condition is sometimes called an insulin reaction and should be treated by giving the patient something sweet to eat or drink like a candy, sugar cubes, juice, or another high sugar snack.

Surgery

Transplantation of a healthy pancreas into a diabetic patient is a successful treatment, however, this transplant is usually done only if a kidney transplant is performed at the same time. Although a pancreas transplant is possible, it is not clear if the potential benefits outweigh the risks of the surgery and drug therapy needed.

Alternative treatment

Since diabetes can be life-threatening if not properly managed, patients should not attempt to treat this condition without medicial supervision. A variety of alternative therapies can be helpful in managing the symptoms of diabetes and supporting patients with the disease. Acupuncture can help relieve the pain associated with diabetic neuropathy by stimulation of cetain points. A qualified practitioner should be consulted. Herbal remedies also may be helpful in managing diabetes. Although there is no herbal substitute for insulin, some herbs may help adjust blood sugar levels or manage other diabetic symptoms. Some options include:

  • fenugreek (Trigonella foenum-graecum ) has been shown in some studies to reduce blood insulin and glucose levels while also lowering cholesterol
  • bilberry (Vaccinium myrtillus ) may lower blood glucose levels, as well as helping to maintain healthy blood vessels
  • garlic (Allium sativum ) may lower blood sugar and cholesterol levels
  • onions (Allium cepa ) may help lower blood glucose levels by freeing insulin to metabolize them
  • cayenne pepper (Capsicum frutescens ) can help relieve pain in the peripheral nerves (a type of diabetic neuropathy)
  • gingko (Gingko biloba ) may maintain blood flow to the retina, helping to prevent diabetic retinopathy

Any therapy that lowers stress levels also can be useful in treating diabetes by helping to reduce insulin requirements. Among the alternative treatments that aim to lower stress are hypnotherapy, biofeedback, and meditation.

Prognosis

Uncontrolled diabetes is a leading cause of blindness, end-stage renal disease, and limb amputations. It also doubles the risks of heart disease and increases the risk of stroke. Eye problems including cataracts, glaucoma, and diabetic retinopathy also are more common in diabetics.

Diabetic peripheral neuropathy is a condition where nerve endings, particularly in the legs and feet, become less sensitive. Diabetic foot ulcers are a particular problem since the patient does not feel the pain of a blister, callous, or other minor injury. Poor blood circulation in the legs and feet contribute to delayed wound healing. The inability to sense pain along with the complications of delayed wound healing can result in minor injuries, blisters, or callouses becoming infected and difficult to treat. In cases of severe infection, the infected tissue begins to break down and rot away. The most serious consequence of this condition is the need for amputation of toes, feet, or legs due to severe infection.

Heart disease and kidney disease are common complications of diabetes. Long-term complications may include the need for kidney dialysis or a kidney transplant due to kidney failure.

Babies born to diabetic mothers have an increased risk of birth defects and distress at birth.

Prevention

Research continues on diabetes prevention and improved detection of those at risk for developing diabetes. While the onset of Type I diabetes is unpredictable, the risk of developing Type II diabetes can be reduced by maintaining ideal weight and exercising regularly. The physical and emotional stress of surgery, illness, pregnancy, and alcoholism can increase the risks of diabetes, so maintaining a healthy lifestyle is critical to preventing the onset of Type II diabetes and preventing further complications of the disease.

KEY TERMS

Cataract A condition where the lens of the eye becomes cloudy.

Diabetic peripheral neuropathy A condition where the sensitivity of nerves to pain, temperature, and pressure is dulled, particularly in the legs and feet.

Diabetic retinopathy A condition where the tiny blood vessels to the retina, the tissues that sense light at the back of the eye, are damaged, leading to blurred vision, sudden blindness, or black spots, lines, or flashing lights in the field of vision.

Glaucoma A condition where pressure within the eye causes damage to the optic nerve, which sends visual images to the brain.

Hyperglycemia A condition where there is too much glucose or sugar in the blood.

Hypoglycemia A condition where there is too little glucose or sugar in the blood.

Insulin A hormone or chemical produced by the pancreas, insulin is needed by cells of the body in order to use glucose (sugar), the body's main source of energy.

Ketoacidosis A condition due to starvation or uncontrolled Type I diabetes. Ketones are acid compounds that form in the blood when the body breaks down fats and proteins. Symptoms include abdominal pain, vomiting, rapid breathing, extreme tiredness, and drowsiness.

Kidney dialysis A process where blood is filtered through a dialysis machine to remove waste products that would normally be removed by the kidneys. The filtered blood is then circulated back into the patient. This process also is called renal dialysis.

Pancreas A gland located behind the stomach that produces insulin.

Resources

PERIODICALS

Crutchfield, Diane B. "Oral Antidiabetic Agents: Back to the Basics." Geriatric Times, May 1, 2003: 20.

"Gestational Diabetes Increases 35% in 10 Years." Health & Medicine Week, March 22, 2004: 220.

Kordella, Terri. "New Combo Pills." Diabetes Forecast, March 2003: 42.

"New Drugs." Drug Topics, November 18, 2002: 73.

"Research: Lower Chromium Levels Linked to Increased Risk of Disease." Diabetes Week, March 29, 2004: 21.

"Standards of Medical Care for Patients with Diabetes Mellitus: American Diabetes Association." Clinical Diabetes, Winter 2003: 27.

"Wider Metformin Use Recommended." Chemist & Druggist, January 11, 2003: 24.

ORGANIZATIONS

American Diabetes Association. 1701 North Beauregard Street, Alexandria, VA 22311. (800) 342-2383. http://www.diabetes.org.

American Dietetic Association. 216 W. Jackson Blvd., Chicago, IL 60606-6995. (312) 899-0040. http://www.eatright.org.

Juvenile Diabetes Foundation. 120 Wall St., 19th Floor, New York, NY 10005. (800) 533-2873. http://www.jdf.org.

National Diabetes Information Clearinghouse. 1 Information Way, Bethesda, MD 20892-3560. (800) 860-8747. [email protected] http://www.niddk.nih.gov/health/diabetes/ndic.htm.

OTHER

Centers for Disease Control. http://www.cdc.gov/nccdphp/ddt/ddthome.htm.

"Insulin-Dependent Diabetes." National Institute of Diabetes and Digestive and Kidney Diseases. National Institutes of Health, NIH Publication No.94-2098.

"Noninsulin-Dependent Diabetes." National Institute of Diabetesand Digestive and Kidney Diseases. National Institutes of Health, NIH Publication No.92-241.

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Diabetes mellitus

Definition

Diabetes mellitus is a chronic disease in which the body is not able to correctly process glucose for cell energy due to either an insufficient amount of the hormone insulin or a physical resistance to the insulin the body does produce. Without proper treatment through medication and/or lifestyle changes, the high blood glucose (or blood sugar) levels caused by diabetes can cause long-term damage to organ systems throughout the body.

Description

There are three types of diabetes mellitus: type 1 (also called juvenile diabetes or insulin-dependent diabetes), type 2 (also called adult-onset diabetes), and gestational diabetes. While type 2 is the most prevalent, consisting of 90 to 95 percent of diabetes patients in the United States, type 1 diabetes is more common in children. Gestational diabetes occurs in pregnancy and resolves at birth.

Every cell in the human body needs energy in order to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates (primarily sugars and starches). Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. However, glucose requires insulin in order to be processed for cellular energy.

Insulin is a hormone or chemical produced by cells in the pancreas, an organ located behind the stomach. Insulin bonds to a receptor site on the outside of a cell. It acts like a key to open a doorway into the cell through which glucose can enter. When there is not enough insulin produced (as is the case with type 1 diabetes) or when the doorway no longer recognizes the insulin key (which happens in type 2 and gestational diabetes), glucose stays in the bloodstream rather entering the cells. The high blood glucose, or blood sugar, levels that result are known as hyperglycemia .

Type 1 diabetes

Type 1 diabetes occurs when the beta cells of the pancreas are damaged and stop producing the hormone insulin. While the exact cause of this cell damage is not completely understood, it is thought to be a combination of environmental and autoimmune factors. Despite the name juvenile diabetes, type 1 diabetes can be diagnosed at any stage of life, although diagnosis in childhood through young adulthood is most common.

Children who develop type 1 diabetes must eventually take regular insulin injections to keep blood glucose levels under control and do the job of the pancreas. Regular home testing of blood sugar levels is also important to make sure that the treatment is working effectively and to avoid a diabetic emergency such as hypoglycemia (low blood sugar) or hyperglycemia (high blood sugar).

Type 2 diabetes

The hallmark characteristic of type 2 diabetes is insulin resistance. The pancreas typically produces enough insulin (often too much insulin); however, cells are resistant to the insulin and it may not work as effectively. Type 2 is the most common form of diabetes, and most individuals with the disease are adults. However, children and adolescents can develop type 2 diabetes too, particularly if they are overweight and have a history of type 2 diabetes in their family .

Type 2 diabetes is treated with diet, exercise , and in some cases, oral medication and/or insulin. Self-monitoring of blood glucose levels is also important to assess how well treatment is working.

Demographics

An estimated 18.2 million Americans live with diabetes, and over 5 million of those remain undiagnosed. Up to 95 percent of diabetes patients in the United States have type 2 diabetes; the vast majority of Americans with diabetes are over 20 years of age. Those under 20 represent only 206,000 of the total cases of diabetes in the United States.

While type 2 diabetes is a growing problem among American youth due to climbing obesity rates and more sedentary lifestyles, type 1 diabetes is more prevalent in children and adolescents. An estimated one in 400 to 500 children have type 1 diabetes.

The American Diabetes Association reports that in 2002, diabetes cost Americans an estimated $132 billion in direct medical costs and indirect expenses such as lost productivity and disability payments.

Causes and symptoms

The causes of diabetes are not completely understood; however, there seem to be both genetic and environmental factors involved in the development of both type 1 and type 2 diabetes, meaning that a person may have a genetic predisposition to developing diabetes, but it takes an environmental factor such as a viral infection or excessive weight gain to actually make the disease surface.

Research has shown that some people who develop diabetes have common genetic markers. In type 1 diabetes, the immune system, the body's defense system against infection, is believed to be triggered by a virus or another microorganism that causes an autoimmune reaction that eventually destroys the insulin-producing cells (i.e., beta cells) in the pancreas. Up to 90 percent of cases of type 1 diabetes are the autoimmune subtype, sometimes called type 1A or immune-mediated diabetes.

The other subtype of type 1 diabetes is called idiopathic, or type 1B diabetes. People who have idiopathic type 1 diabetes also experience beta cell destruction, but it is due to a chromosomal abnormality or an unknown cause rather than any autoimmune process. Only tests for islet cell antibodies and other autoimmune markers can differentiate between the two subtypes, and because testing can be costly and treatment for both is the same (i.e., insulin), a physician may not necessarily order tests for autoimmunity.

Finally, damage caused by diseases of the pancreas (such as pancreatitis), endocrine disorders (e.g., endocrine tumors), and drugs or toxins can also destroy beta cell function.

In type 2 diabetes, family history, age, weight, activity level, and ethnic background can all play a role in the genesis of the disease. Individuals who are at high risk of developing type 2 diabetes mellitus include the following groups:

  • people who are overweight or obese (more than 20 percent above their ideal body weight)
  • people who have a parent or sibling with type 2 diabetes
  • those who belong to a high-risk ethnic population (African-American, Native American, Asian-American, Hispanic, or Pacific Islander)
  • people who live a sedentary lifestyle (i.e., exercise less than three times a week)
  • women who have been diagnosed with gestational diabetes or have delivered a baby weighing more than 9 lbs (4 kg)
  • people with high blood pressure (140/90 mmHg or above)
  • people with high density lipoprotein cholesterol (HDL, or "good" cholesterol) level less than or equal to 35 mg/dl and/or a triglyceride level greater than or equal to 250 mg/dl

Several common medications can cause chronic high blood sugar levels and/or promote insulin resistance. These include atypical antipsychotics, beta blockers, corticosteroids, diuretics, estrogens, lithium, protease inhibitors, niacin, and some thyroid preparations.

Both type 1 and type 2 diabetes share similar symptoms caused by chronically high blood glucose levels.

Symptoms of both type 1 and type 2 diabetes include:

  • excessive thirst
  • frequent urination
  • weight loss
  • increased appetite
  • unexplained fatigue
  • slow healing cuts, bruises , and wounds
  • frequent or lingering infections (e.g., urinary tract infection)
  • mood swings and irritability
  • blurred vision
  • headache
  • high blood pressure
  • dry and itchy skin
  • tingling, numbness , or burning in hands or feet

Symptoms of diabetes can develop suddenly (over days or weeks) in previously healthy children or adolescents, or can develop gradually, particularly in the case of type 2 diabetes.

Children and adolescents sometimes develop a condition known as diabetic ketoacidosis (DKA) at the time of their diagnosis. Ketones are acid compounds that form in the blood when the body breaks down fats and proteins for energy. When blood sugars are high (i.e., over 249 mg/dl, or 13.8 mmol/L) for prolonged periods of time, ketones build up in the bloodstream to dangerous levels. Symptoms of DKA include abdominal pain , excessive thirst, nausea and vomiting , rapid breathing, extreme lethargy, and drowsiness. Patients with ketoacidosis will also have a fruity or sweet breath odor. Left untreated, this condition can lead to coma and has the potential to be fatal. DKA is more common in people with type 1 diabetes, although it can occur in type 2 diabetes as well.

Symptoms of type 2 diabetes can begin so gradually that a person may not know that he or she has it. It is not unusual for type 2 diabetes to be detected while a patient is seeing a doctor about another health concern that is actually being caused by the yet undiagnosed diabetes, such as heart disease, chronic infections (e.g., urinary tract infections, yeast infections), blurred vision, numbness in the feet and legs, or slow-healing wounds.

When to call the doctor

If left untreated, diabetes is a life-threatening condition. Any child displaying symptoms of diabetes should be taken to a doctor or emergency care facility for evaluation immediately.

Diagnosis

Diagnosis of diabetes is suspected based on symptoms and confirmed by blood tests that measure the level of glucose in blood plasma. Dipstick or reagent test strips that measure glucose in the urine can only detect glucose levels above 180 mg/dl and are non-specific, so they are not useful in the diagnosis of diabetes. However, they are a non-invasive way to obtain a fast and simple reading that a physician might use as a basis for ordering further diagnostic blood tests for diabetes, particularly in children.

Blood tests are the gold standard for the diagnosis of both type 1 and type 2 diabetes in children and adults. The American Diabetes Association recommends that a random plasma glucose, fasting plasma glucose, or oral glucose tolerance test (OGTT) be used for diagnosis of diabetes. The OGTT is commonly used as a screening measure for gestational diabetes. Fasting plasma glucose is the test of choice unless a child is exhibiting classic symptoms of diabetes, in which case a random (or casual) plasma glucose test is acceptable.

Unless hyperglycemia is obvious (e.g., blood glucose levels are extremely high or the child experiences DKA), the fasting or random plasma glucose test should be confirmed on a subsequent day with a repeat test.

Fasting plasma glucose test

Blood is drawn from a vein in the child's arm following an eight-hour fast (i.e., no food or drink), usually in the morning before breakfast. The red blood cells are separated from the sample and the amount of glucose is measured in the remaining plasma. A fasting plasma glucose level of 126 mg/dl (7.0 mmol/l) or higher indicates diabetes (with a confirming retest on a subsequent day).

Random plasma glucose test

Blood is drawn at any time of day, regardless of whether the patient has eaten. A random plasma glucose concentration of 200 mg/dl (11.1 mmol/l) or higher in the presence of symptoms indicates diabetes.

Oral glucose tolerance test

Blood samples are taken both before and several times after a patient drinks 75 grams of a glucose-based beverage. If plasma glucose levels taken two hours after the glucose drink is consumed are 200 mg/dl (11.1 mmol/L) or higher, the test is diagnostic of diabetes (and should be confirmed on a subsequent day if possible).

Although the same diagnostic blood tests are used for both types of diabetes, whether a child is diagnosed as type 1 or type 2 can typically be determined based on her personal and medical history. The majority of children diagnosed in childhood are type 1, but if blood test results indicate prediabetes and a child is significantly overweight and has a history of type 2 diabetes in her family, type 2 is a possibility.

Further blood tests can help to differentiate between type 1 and type 2 when the diagnosis is unclear. One of these is an assessment of c-peptide levels, a protein released along with insulin that can help a physician determine whether or not a patient is producing sufficient amounts of insulin. The other is a GAD (Glutamic Acid Decarboxylase) autoantibody test. The presence of GAD autoantibodies may indicate the beginning of the autoimmune process that destroys pancreatic beta cells.

Treatment

Children with type 1 diabetes must take insulin injections or infusions. Their dosage needs may change over time. Sometimes children will experience a decreased need for insulin once blood sugars are brought under control following diagnosis. Their insulin needs may go down, and in some cases, they can stop taking injections for a time. This phenomenon, known as the honeymoon period, can last anywhere from a few days to months.

Children with diabetes and their parents should learn to operate a home blood glucose monitor. Home testing can prevent dangerous highs and lows and help parents and children understand how food and exercise impact blood sugar levels. Blood glucose levels taken before meals are also used to calculate dose size of insulin. A small needle or lancet is used to prick the finger or alternate site and a drop of blood is collected on a test strip that is inserted into a monitor. The monitor then calculates and displays the blood glucose reading on a screen. Although individual blood glucose targets should be determined by a medical professional in light of a child's medical history, the general goal is to keep them as close to normal (i.e., 90 to 130 mg/dl or 5 to 7.2 mmol/L before meals) as possible.

Insulin

Children with type 1 diabetes need daily injections of insulin to help their bodies use glucose. The amount and type of insulin required depends on the height, weight, age, food intake, and activity level of the individual diabetic patient. Some patients with type 2 diabetes may also need to use insulin injections if their diabetes cannot be controlled with diet, exercise, and oral medication. Injections are given subcutaneously, that is, just under the skin, using a small needle and syringe, an insulin pen injector, an insulin infusion pump, or a jet injector device. Injection sites can be anywhere on the body where there is a layer of fat available, including the upper arm, abdomen, or upper thigh.

Insulin may be given as an injection of a single dose of one type of insulin once a day, or different types of insulin can be mixed and given in one dose or split into two or more doses during a day. Patients who require multiple injections over the course of a day may be able to use an insulin pump that administers small doses of insulin on demand. The small battery-operated pump is worn outside the body and is connected to a cannula (a thin, flexible plastic tube) that is inserted into the abdomen called an insertion set. Pumps are programmed to infuse a small, steady infusion of insulin (called a basal dose) throughout the day, and larger doses (called boluses) before meals. Because of the basal infusion, pumps can offer many children much tighter control over their blood glucose levels and more flexibility with their diet than insulin shots afford them.

Regular insulin is fast-acting and starts to work within 15 to 30 minutes, with its peak glucose-lowering effect about two hours after it is injected. Its effects last for about four to six hours. NPH (neutral protamine Hagedorn) and Lente insulin are intermediate-acting, starting to work within one to three hours and lasting up to 18 to 26 hours. Ultra-lente is a long-acting form of insulin that starts to work within four to eight hours and lasts 28 to 36 hours. Peakless, or basal-action insulin (insulin glargine, or Lantus) starts working in 15 minutes and has a duration of between 18 and 26 hours.

Nutritional concerns

Because dietary carbohydrates are the primary source of glucose for the body (the other source being the liver), it is very important that children with diabetes learn to read labels and be aware of the amount of carbohydrates in the foods they eat. Children and their parents are usually advised to consult a registered dietitian (RD) to create an individualized, easy to manage food plan that fits their family's health and lifestyle needs. A well-balanced, nutritious diet provides approximately 50 to 60 percent of calories from carbohydrates, approximately 10 to 20 percent of calories from protein, and less than 30 percent of calories from fat. The number of calories required depends on age, weight, and activity level. An RD can also teach the family how to use either the dietary exchange lists or carbohydrate counting system to monitor food intake.

Each food exchange contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient's diet plan will consist of a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at meal times and as snacks. Patients have flexibility in choosing which foods they eat as long as they stick with the number of exchanges prescribed by their RD based on their caloric requirements.

Carbohydrate counting involves totaling the grams of carbohydrates in the foods your child eats to ensure the child does not exceed her goal for the day. In the simple-carb counting method, one carbohydrate choice or unit equals 15 grams of carbohydrates (which is equivalent to one starch or fruit exchange in the exchange method). The number of carb choices allowed daily is based on caloric requirements.

Children with type 1 diabetes who use fast-acting insulin before meals may find that carb counting gives them tighter control of their blood glucose levels, since they can compute the number of insulin units based on both their carbohydrate intake (called the carbohydrate to insulin ratio) and before-meal blood glucose readings.

Dietary changes and moderate exercise are usually the first treatments implemented in type 2 diabetes. Weight loss may be an important goal in helping overweight children and adolescents control their blood sugar levels. Exercise helps keep blood glucose levels down and has other health benefits, as well.

Oral medications

Children with type 2 diabetes may be prescribed oral medications if they are unable to keep their blood glucose levels under control with dietary and exercise measures. As of 2004, metformin was the only oral medication approved by the U.S. FDA for use in children over age ten. Metformin (trade name Glucophage) is in the biguanide class of drugs and works by reducing the amount of glucose the liver produces and the amount of circulating insulin in the body. Other adult type 2 diabetes medications, such as sulfonylureas and meglitinide drugs, which work by increasing insulin production, may be prescribed off-label for pediatric use.

Transplants

Transplantation of a healthy pancreas into a patient with type 1 diabetes can eliminate the need for insulin injections; however, this transplant is typically done only if a kidney transplant is performed at the same time. Although a pancreas transplant is possible, it is not clear if the potential benefits outweigh the risks of the surgery and life-long drug therapy needed to prevent organ rejection, particularly in the case of children.

A second type of transplant procedure, as of 2004 in experimental clinical trials and not available to children, is an islet cell transplant. In this type of treatment, insulin-producing islet cells are harvested from a donor pancreas and injected into the liver of a recipient, where they attach to new blood vessels and (ideally) begin producing insulin. A lifetime regimen of immunosuppressive drugs is required to prevent rejection of the transplanted cells.

Prognosis

As of 2004 diabetes is a chronic and incurable disease. While stem cell research holds great promise for future therapies and potential cures, as of the early 2000s the best hope for keeping children well with diabetes and avoiding long-term complications is maintaining good blood glucose control. The landmark Diabetes Control and Complications Trial (DCCT) found that patients with type 1 diabetes who kept their blood sugar levels as close to normal as possible reduced their risk for developing diabetic eye disease by 76 percent, for diabetic kidney disease by 50 percent, and for diabetic neuropathy by 60 percent.

Diabetes and its related complications was the sixth leading cause of death in 2000. According to the National Institutes of Health, cardiovascular, or heart and blood vessel disease, is the leading cause of diabetes-related death. Uncontrolled diabetes is a leading cause of blindness, end-stage renal disease, and limb amputations. Eye problems including cataracts, glaucoma, and diabetic retinopathy also are more common in people with diabetes.

Diabetic neuropathy is the result of nerve damage caused by uncontrolled diabetes. Autonomic neuropathy affects the autonomic nervous system and can cause gastroparesis (nerve damage of the stomach), neurogenic bladder (nerve damage of the urinary bladder), and a host of other problems with involuntary functions of the nervous system.

In peripheral neuropathy (PN), nerve damage in the extremities (e.g., the legs and feet) causes numbness, pain, and burning. Diabetic foot ulcers are a particular problem since frequently the patient does not feel the pain of a blister, callous, or other minor injury. Poor blood circulation in the legs and feet contribute to delayed wound healing. The inability to sense pain along with the complications of delayed wound healing can result in minor injuries, blisters, or calluses becoming infected and difficult to treat. The most serious consequence of this condition is the potential for amputation of toes, feet, or legs due to severe infection.

Diabetic kidney disease is another common complications of diabetes. Long-term complications may include the need for kidney dialysis or a kidney transplant due to kidney failure. Diabetes is the number one cause of chronic kidney failure in America.

Children and adults with the autoimmune form of type 1 diabetes are also at greater risk for other autoimmune disorders, including thyroid disease, celiac sprue (sometimes called gluten intolerance), autoimmune hepatitis, myasthenia gravis, and pernicious anemia.

Prevention

As of 2004 research continues on diabetes prevention and improved detection of those at risk for developing diabetes. While the onset of type 1 diabetes is unpredictable, the risk of developing type 2 diabetes may be reduced by maintaining ideal weight and exercising regularly. Both physical and emotional stress can cause increases in blood glucose levels, so getting regular immunizations and well-child check-ups, practicing good sleep and hygiene habits, encouraging emotional and social growth, and maintaining a stress-controlled lifestyle is important for children with type 1 or type 2 diabetes.

Parental concerns

Parents of children with diabetes must work with their child's teachers and school administrators to ensure that their child is able to test her blood sugars regularly, take insulin as needed, and have access to food or drink to treat a low. Someone at school should also be trained in how to administer a glucagon injection, an emergency treatment for a hypoglycemic episode when a child loses consciousness.

Section 504 of the Rehabilitation Act of 1973 enables parents to develop both a Section 504 plan (which describes a child's medical needs) and an individualized education plan (IEP) (which describes what special accommodations a child requires to address those needs). An IEP should cover such issues as blood glucose monitoring, dietary plans, and treating highs and lows. If school staff has little to no experience with diabetes, bringing in a certified diabetes educator (CDE) to offer basic training may be useful.

Children with diabetes can lead an active life and enjoy most of the activities and foods their peers do, with a few precautions to avoid blood sugar highs or lows. A certified diabetes educator that has experience working with children can help them understand the importance of regular testing as well as methods for minimizing discomfort. Diabetes summer camps, where children can learn about diabetes care in the company of peers and counselors who also live with the disease, may be useful from both a health and a social standpoint. In addition, peer support groups can sometimes help children come to terms with their diabetes.

Hypoglycemia, or low blood sugar, can be caused by too much insulin, too little food (or eating too late to coincide with the action of the insulin), alcohol consumption, or increased exercise. A child with symptoms of hypoglycemia may be hungry, cranky, confused, and tired. The patient may become sweaty and shaky. Left untreated, a child can lose consciousness or have a seizure. This condition is sometimes called an insulin reaction and should be treated by giving the patient something sweet to eat or drink like candy, juice, glucose gel, or another high sugar snack. A child who loses consciousness due to a low should never be given food or drink due to the risk of choking . In these cases, a glucagon injection should be administered and the child should be taken to the nearest emergency care facility.

While exercise can lower blood glucose levels, children with diabetes can and do excel in sports . Proper hydration, frequent testing, and a before-game or practice snack can prevent hypoglycemia. Coaches or another onsite adult should be aware of a child's medical condition and be prepared to treat a hypoglycemic attack if necessary.

The other potential danger to a child with diabetesdiabetic ketoacidosisis uncommon and most likely to occur prior to a diagnosis. It may also happen if insulin is discontinued or if the body is under stress due to illness or injury. Ketones in the urine can be detected using dipstick tests (e.g., Ketostix), or detected using a home ketone blood monitor. Early detection facilitates early treatment and can prevent full-blown DKA.

Because the symptoms of DKA can mimic the flu, and the flu can increase blood sugar levels, a child who comes down with a flu-like illness should be monitored closely and tested regularly. An increase in insulin may also be necessary; parents of children with diabetes should talk with their pediatrician about a sick day plan for their child before they need it.

KEY TERMS

Diabetic retinopathy A condition seen most frequently in individuals with poorly controlled diabetes mellitus where the tiny blood vessels to the retina, the tissues that sense light at the back of the eye, are damaged. This damage causes blurred vision, sudden blindness, or black spots, lines, or flashing light in the field of vision.

Glucagon A hormone produced in the pancreas that changes glycogen, a carbohydrate stored in muscles and the liver, into glucose. It can be used to relax muscles for a procedure such as duodenography. An injectable form of glucagon is sometimes used to treat insulin shock.

Honeymoon phase A period of time shortly following diagnosis of type 1 diabetes during which a child's need for insulin may decrease or disappear altogether. The honeymoon phase is transitional, and insulin requirements eventually increases again.

Hyperglycemia A condition characterized by excessively high levels of glucose in the blood. It occurs when the body does not have enough insulin or cannot use the insulin it does have to turn glucose into energy.

Hypoglycemia A condition characterized by abnormally low levels of glucose in the blood.

Insulin A hormone or chemical produced by the pancreas that is needed by cells of the body in order to use glucose (sugar), a major source of energy for the human body.

Ketoacidosis Usually caused by uncontrolled type I diabetes, when the body isn't able to use glucose for energy. As an alternate source of energy, fat cells are broken down, producing ketones, toxic compounds that make the blood acidic. Symptoms of ketoacidosis include excessive thirst and urination, abdominal pain, vomiting, rapid breathing, extreme tiredness, and drowsiness.

Off-label use Prescribing a drug for a population (e.g., pediatric) or condition for which it was not originally approved by the U.S. FDA. For example, sulfonylurea drugs are not FDA approved for use in children with type 2 diabetes due to a lack of clinical studies in pediatric populations, but a physician may prescribe them in an off-label use of the drug.

Prediabetes A precursor condition to type 2 diabetes, sometimes called impaired glucose tolerance or impaired fasting glucose. Prediabetes is clinically defined as individuals who have elevated blood glucose levels that are not diagnostic of type 2 diabetes but are above normal (for the fasting plasma glucose test, this measurement would be 100 to 125 mg/dL (5.6 to 6.9 mmol/L).

See also Hypoglycemia.

Resources

BOOKS

The American Diabetes Association Complete Guide to Diabetes, 3rd ed. Alexandria, VA: American Diabetes Association, 2002.

Brackenridge, Betty, and Richard Rubin. Sweet Kids: How to Balance Diabetes Control and Good Nutrition with Family Peace, 2nd ed. Alexandria, VA: American Diabetes Association, 2002.

Ford-Martin, Paula, with Ian Blumer. The Everything Diabetes Book. Avon, MA: Adams Media, 2004.

ORGANIZATIONS

American Diabetes Association. 1701 North Beauregard St., Alexandria, VA 22311. Web site: <www.diabetes.org>.

American Dietetic Association. 216 W. Jackson Blvd., Chicago, IL 606066995. Web site: <www.eatright.org>.

Children with Diabetes. 5689 Chancery Place, Hamilton, OH 45011. Web site: <www.childrenwithdiabetes.org>.

Juvenile Diabetes Research Foundation. 120 Wall St., 19th Floor, New York, NY 10005. Web site: <www.jdrf.org>.

National Diabetes Information Clearinghouse. 1 Information Way, Bethesda, MD 208923560. Web site: <www.niddk.nih.gov/health/diabetes/ndic.htm>.

WEB SITES

"2004 Clinical Practice Recommendations." Diabetes Care, January, 2004. Available online at <http://care.diabetesjournals.org/content/vol27/suppl_1/> (accessed December 26, 2004).

Ford-Martin, Paula. "About Diabetes" Available online at <http://diabetes.about.com> (accessed December 26, 2004).

Mendosa, David. David Mendosa's Diabetes Directory. Available online at <www.mendosa.com/diabetes.htm> (accessed December 26, 2004).

Paula Ford-Martin Altha Roberts Edgren Teresa G. Odle

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Diabetes Mellitus

Definition

Description

Causes and symptoms

Diagnosis

Treatment

Prognosis

Prevention

Resources

Definition

Diabetes mellitus is a condition in which the pancreas no longer produces enough insulin or cells stop responding to the insulin that is produced, so that glucose in the blood cannot be absorbed into the cells of the body. Symptoms include frequent urination, lethargy, excessive thirst, and hunger. The treatment includes changes in diet, oral medications, and in some cases, daily injections of insulin.

Description

Diabetes mellitus is a chronic disease that causes serious health complications including renal (kidney) failure, heart disease, stroke, and blindness. Approximately 17 million Americans have diabetes. Unfortunately, as many as one-half are unaware they have it.

Target blood glucose levels for people with diabetes

Before meals90 to 130
1 to 2 hours after the start of a mealless than 180

source: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, U.S. Department of Health and Human Services.

(Illustration by GGS Information Services/Thomson Gale.)

Background

Every cell in the human body needs energy in order to function. The body’s primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates (sugars and starches). Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. Insulin is a hormone or chemical produced by cells in the pancreas, an organ located behind the stomach. Insulin bonds to a receptor site on the outside of cell and acts like a key to open a doorway into the cell through which glucose can enter. Some of the glucose can be converted to concentrated energy sources like glycogen or fatty acids and saved for later use. When there is not enough insulin produced or when the doorway no longer recognizes the insulin key, glucose stays in the blood rather entering the cells.

The body will attempt to dilute the high level of glucose in the blood, a condition called hyperglyce-mia, by drawing water out of the cells and into the bloodstream in an effort to dilute the sugar and excrete it in the urine. It is not unusual for people with undiag-nosed diabetes to be constantly thirsty, drink large quantities of water, and urinate frequently as their bodies try to get rid of the extra glucose. This creates high levels of glucose in the urine.

At the same time that the body is trying to get rid of glucose from the blood, the cells are starving for glucose and sending signals to the body to eat more food, thus making patients extremely hungry. To provide energy for the starving cells, the body also tries to convert fats and proteins to glucose. The breakdown of fats and proteins for energy causes acid compounds called ketones to form in the blood. Ketones also will be excreted in the urine. As ketones build up in the blood, a condition called ketoa-cidosis can occur. This condition can be life threatening if left untreated, leading to coma and death.

Types of diabetes mellitus

Type I diabetes, sometimes called juvenile diabetes, begins most commonly in childhood or adolescence. In this form of diabetes, the body produces.

KEY TERMS

Cataract— A condition where the lens of the eye becomes cloudy.

Diabetic peripheral neuropathy— A condition where the sensitivity of nerves to pain, temperature, and pressure is dulled, particularly in the legs and feet.

Diabetic retinopathy— A condition where the tiny blood vessels to the retina, the tissues that sense light at the back of the eye, are damaged, leading to blurred vision, sudden blindness, or black spots, lines, or flashing lights in the field of vision.

Glaucoma— A condition where pressure within the eye causes damage to the optic nerve, which sends visual images to the brain.

Hyperglycemia— A condition where there is too much glucose or sugar in the blood.

Hypoglycemia— A condition where there is too little glucose or sugar in the blood.

Insulin— A hormone or chemical produced by the pancreas, insulin is needed by cells of the body in order to use glucose (sugar), the body’s main source of energy.

Ketoacidosis— A condition due to starvation or uncontrolled Type I diabetes. Ketones are acid compounds that form in the blood when the body breaks down fats and proteins. Symptoms include abdominal pain, vomiting, rapid breathing, extreme tiredness, and drowsiness.

Kidney dialysis— A process where blood is filtered through a dialysis machine to remove waste products that would normally be removed by the kidneys. The filtered blood is then circulated back into the patient. This process also is called renal dialysis.

Pancreas— A gland located behind the stomach that produces insulin.

little or no insulin. It is characterized by a sudden onset and occurs more frequently in populations descended from Northern European countries (Finland, Scotland, Scandinavia) than in those from Southern European countries, the Middle East, or Asia. In the United States, approximately three people in 1,000 develop Type I diabetes. This form also is called insulin-dependent diabetes because people who develop this type need to have daily injections of insulin.

Brittle diabetics are a subgroup of Type I where patients have frequent and rapid swings of blood sugar levels between hyperglycemia (a condition where there is too much glucose or sugar in the blood) and hypoglycemia (a condition where there are abnormally low levels of glucose or sugar in the blood). These patients may require several injections of different types of insulin during the day to keep the blood sugar level within a fairly normal range.

The more common form of diabetes, Type II, occurs in approximately 3–5% of Americans under 50 years of age, and increases to 10–15% in those over 50. More than 90% of the diabetics in the United States are Type II diabetics. Sometimes called age-onset or adult-onset diabetes, this form of diabetes occurs most often in people who are overweight and who do not exercise. It is also more common in people of Native American, Hispanic, and African-American descent. People who have migrated to Western cultures from East India, Japan, and Australian Aboriginal cultures also are more likely to develop Type II diabetes than those who remain in their original countries.

Type II is considered a milder form of diabetes because of its slow onset (sometimes developing over the course of several years) and because it usually can be controlled with diet and oral medication. The consequences of uncontrolled and untreated Type II diabetes, however, are the just as serious as those for Type I. This form is also called noninsulin-dependent diabetes, a term that is somewhat misleading. Many people with Type II diabetes can control the condition with diet and oral medications, however, insulin injections are sometimes necessary if treatment with diet and oral medication is not working.

Another form of diabetes called gestational diabetes can develop during pregnancy and generally resolves after the baby is delivered. This diabetic condition develops during the second or third trimester of pregnancy in about 2% of pregnancies. In 2004, incidence of gestational diabetes were reported to have increased 35% in 10 years. Children of women with gestational diabetes are more likely to be born prematurely, have hypoglycemia, or have severe jaundice at birth. The condition usually is treated by diet, however, insulin injections may be required. These women who have diabetes during pregnancy are at higher risk for developing Type II diabetes within 5–10 years.

Diabetes also can develop as a result of pancreatic disease, alcoholism, malnutrition, or other severe illnesses that stress the body.

Causes and symptoms

Causes

The causes of diabetes mellitus are unclear, however, there seem to be both hereditary (genetic factors passed on in families) and environmental factors involved. Research has shown that some people who develop diabetes have common genetic markers. In Type I diabetes, the immune system, the body’s defense system against infection, is believed to be triggered by a virus or another microorganism that destroys cells in the pancreas that produce insulin. In Type II diabetes, age, obesity , and family history of diabetes play a role.

In Type II diabetes, the pancreas may produce enough insulin, however, cells have become resistant to the insulin produced and it may not work as effectively. Symptoms of Type II diabetes can begin so gradually that a person may not know that he or she has it. Early signs are lethargy, extreme thirst, and frequent urination. Other symptoms may include sudden weight loss, slow wound healing, urinary tract infections, gum disease, or blurred vision. It is not unusual for Type II diabetes to be detected while a patient is seeing a doctor about another health concern that is actually being caused by the yet undiagnosed diabetes.

Individuals who are at high risk of developing Type II diabetes mellitus include people who:

  • are obese (more than 20% above their ideal body weight)
  • have a relative with diabetes mellitus
  • belong to a high-risk ethnic population (African-American, Native American, Hispanic, or Native Hawaiian)
  • have been diagnosed with gestational diabetes or have delivered a baby weighing more than 9 lbs (4 kg)
  • have high blood pressure (140/90 mmHg or above)
  • have a high density lipoprotein cholesterol level less than or equal to 35 mg/dL and/or a triglyceride level greater than or equal to 250 mg/dL
  • have had impaired glucose tolerance or impaired fasting glucose on previous testing

Several common medications can impair the body’s use of insulin, causing a condition known as secondary diabetes. These medications include treatments for high blood pressure (furosemide, clonidine, and thiazide diuretics), drugs with hormonal activity (oral contraceptives, thyroid hormone, progestins, and glucocorticorids), and the anti-inflammation drug indomethacin. Several drugs that are used to treat mood disorders (such as anxiety and depression) also can impair glucose absorption. These drugs include haloperidol, lithium carbonate, phenothia-zines, tricyclic antidepressants, and adrenergic agonists. Other medications that can cause diabetes symptoms include isoniazid, nicotinic acid, cimetidine, and heparin. A 2004 study found that low levels of the essential mineral chromium in the body may be linked to increased risk for diseases associated with insulin resistance.

Symptoms

Symptoms of diabetes can develop suddenly (over days or weeks) in previously healthy children or adolescents, or can develop gradually (over several years) in overweight adults over the age of 40. The classic symptoms include feeling tired and sick, frequent urination, excessive thirst, excessive hunger, and weight loss.

Ketoacidosis, a condition due to starvation or uncontrolled diabetes, is common in Type I diabetes. Ketones are acid compounds that form in the blood when the body breaks down fats and proteins. Symptoms include abdominal pain, vomiting, rapid breathing, extreme lethargy, and drowsiness. Patients with ketoacidosis will also have a sweet breath odor. Left untreated, this condition can lead to coma and death.

With Type II diabetes, the condition may not become evident until the patient presents for medical treatment for some other condition. A patient may have heart disease, chronic infections of the gums and urinary tract, blurred vision, numbness in the feet and legs, or slow-healing wounds. Women may experience genital itching.

Diagnosis

Diabetes is suspected based on symptoms. Urine tests and blood tests can be used to confirm a diagnose of diabetes based on the amount of glucose found. Urine can also detect ketones and protein in the urine that may help diagnose diabetes and assess how well the kidneys are functioning. These tests also can be used to monitor the disease once the patient is on a standardized diet, oral medications, or insulin.

Urine tests

Clinistix and Diastix are paper strips or dipsticks that change color when dipped in urine. The test strip is compared to a chart that shows the amount of glucose in the urine based on the change in color. The level of glucose in the urine lags behind the level of glucose in the blood. Testing the urine with a test stick, paper strip, or tablet that changes color when sugar is present is not as accurate as blood testing, however it can give a fast and simple reading.

Ketones in the urine can be detected using similar types of dipstick tests (Acetest or Ketostix). Ketoaci-dosis can be a life-threatening situation in Type I diabetics, so having a quick and simple test to detect ketones can assist in establishing a diagnosis sooner.

Another dipstick test can determine the presence of protein or albumin in the urine. Protein in the urine can indicate problems with kidney function and can be used to track the development of renal failure. A more sensitive test for urine protein uses radioactively tagged chemicals to detect microalbuminuria, small amounts of protein in the urine, that may not show up on dipstick tests.

Blood tests

FASTING GLUCOSE TEST . Blood is drawn from a vein in the patient’s arm after a period at least eight hours when the patient has not eaten, usually in the morning before breakfast. The red blood cells are separated from the sample and the amount of glucose is measured in the remaining plasma. A plasma level of 7.8 mmol/L (200 mg/L) or greater can indicate diabetes. The fasting glucose test is usually repeated on another day to confirm the results.

POSTPRANDIAL GLUCOSE TEST . Blood is taken right after the patient has eaten a meal.

ORAL GLUCOSE TOLERANCE TEST . Blood samples are taken from a vein before and after a patient drinks a thick, sweet syrup of glucose and other sugars. In a non-diabetic, the level of glucose in the blood goes up immediately after the drink and then decreases gradually as insulin is used by the body to metabolize, or absorb, the sugar. In a diabetic, the glucose in the blood goes up and stays high after drinking the sweetened liquid. A plasma glucose level of 11.1 mmol/L (200 mg/dL) or higher at two hours after drinking the syrup and at one other point during the two-hour test period confirms the diagnosis of diabetes.

A diagnosis of diabetes is confirmed if there are symptoms of diabetes and a plasma glucose level of at least 11.1 mmol/L, a fasting plasma glucose level of at least 7 mmol/L; or a two-hour plasma glucose level of at least 11.1 mmol/L during an oral glucose tolerance test.

Home blood glucose monitoring kits are available so patients with diabetes can monitor their own levels. A small needle or lancet is used to prick the finger and a drop of blood is collected and analyzed by a monitoring device. Some patients may test their blood glucose levels several times during a day and use this information to adjust their doses of insulin.

Treatment

There is currently no cure for diabetes. The condition, however, can be managed so that patients can live a relatively normal life. Treatment of diabetes focuses on two goals: keeping blood glucose within normal range and preventing the development of long-term complications. Careful monitoring of diet, exercise, and blood glucose levels are as important as the use of insulin or oral medications in preventing complications of diabetes. In 2003, the American Diabetes Association updated its Standards of Care for the management of diabetes. These standards help manage health care providers in the most recent recommendations for diagnosis and treatment of the disease.

Dietary changes

Diet and moderate exercise are the first treatments implemented in diabetes. For many Type II diabetics, weight loss may be an important goal in helping them to control their diabetes. A well-balanced, nutritious diet provides approximately 50–60% of calories from carbohydrates, approximately 10–20% of calories from protein, and less than 30% of calories from fat. The number of calories required by an individual depends on age, weight, and activity level. The calorie intake also needs to be distributed over the course of the entire day so surges of glucose entering the blood system are kept to a minimum.

Keeping track of the number of calories provided by different foods can become complicated, so patients usually are advised to consult a nutritionist or dietitian. An individualized, easy to manage diet plan can be set up for each patient. Both the American Diabetes Association and the American Dietetic Association recommend diets based on the use of food exchange lists. Each food exchange contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient’s diet plan will consist of a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at meal times and as snacks. Patients have flexibility in choosing which foods they eat as long as they stick with the number of exchanges prescribed.

For many Type II diabetics, weight loss is an important factor in controlling their condition. The food exchange system, along with a plan of moderate exercise, can help them lose excess weight and improve their overall health.

Oral medications

Oral medications are available to lower blood glucose in Type II diabetics. In 1990, 23.4 outpatient prescriptions for oral antidiabetic agents were dispensed. By 2001, the number had increased to 91.8 million prescriptions. Oral antidiabetic agents accounted for more than $5 billion dollars in worldwide retail sales per year in the early twenty-first century and were the fastest-growing segment of diabetes drugs. The drugs first prescribed for Type II diabetes are in a class of compounds called sulfonylureas and include tolbutamide, tolazamide, acetohexamide, and chlorpropamide. Newer drugs in the same class are now available and include glyburide, glimeperide, and glipizide. How these drugs work is not well understood, however, they seem to stimulate cells of the pancreas to produce more insulin. New medications that are available to treat diabetes include metformin, acarbose, and troglitizone. The choice of medication depends in part on the individual patient profile. All drugs have side effects that may make them inappropriate for particular patients. Some for example, may stimulate weight gain or cause stomach irritation, so they may not be the best treatment for someone who is already overweight or who has stomach ulcers. Others, like metformin, have been shown to have positive effects such as reduced cardiovascular mortality, but but increased risk in other situations. While these medications are an important aspect of treatment for Type II diabetes, they are not a substitute for a well planned diet and moderate exercise. Oral medications have not been shown effective for Type I diabetes, in which the patient produces little or no insulin.

Constant advances are being made in development of new oral medications for persons with diabetes. In 2003, a drug called Metaglip combining glipizide and metformin was approved in a dingle tablet. Along with diet and exercise, the drug was used as initial therapy for Type 2 diabetes. Another drug approved by the U.S. Food and Drug Administration (FDA) combines metformin and rosiglitazone (Avandia), a medication that increases muscle cells’ sensitivity to insulin. It is marketed under the name Avandamet. So many new drugs are under development that it is best to stay in touch with a physician for the latest information; physicians can find the best drug, diet and exercise program to fit an individual patient’s need.

Insulin

Patients with Type I diabetes need daily injections of insulin to help their bodies use glucose. The amount and type of insulin required depends on the height, weight, age, food intake, and activity level of the individual diabetic patient. Some patients with Type II diabetes may need to use insulin injections if their diabetes cannot be controlled with diet, exercise, and oral medication. Injections are given subcutaneously, that is, just under the skin, using a small needle and syringe. Injection sites can be anywhere on the body where there is looser skin, including the upper arm, abdomen, or upper thigh.

Purified human insulin is most commonly used, however, insulin from beef and pork sources also are available. Insulin may be given as an injection of a single dose of one type of insulin once a day. Different types of insulin can be mixed and given in one dose or split into two or more doses during a day. Patients who require multiple injections over the course of a day may be able to use an insulin pump that administers small doses of insulin on demand. The small battery-operated pump is worn outside the body and is connected to a needle that is inserted into the abdomen. Pumps can be programmed to inject small doses of insulin at various times during the day, or the patient may be able to adjust the insulin doses to coincide with meals and exercise.

Regular insulin is fast-acting and starts to work within 15–30 minutes, with its peak glucose-lowering effect about two hours after it is injected. Its effects last for about four to six hours. NPH (neutral protamine Hagedorn) and Lente insulin are intermediate-acting, starting to work within one to three hours and lasting up to 18–26 hours. Ultra-lente is a long-acting form of insulin that starts to work within four to eight hours and lasts 28–36 hours.

Hypoglycemia, or low blood sugar, can be caused by too much insulin, too little food (or eating too late to coincide with the action of the insulin), alcohol consumption, or increased exercise. A patient with symptoms of hypoglycemia may be hungry, cranky, confused, and tired. The patient may become sweaty and shaky. Left untreated, the patient can lose consciousness or have a seizure. This condition is sometimes called an insulin reaction and should be treated by giving the patient something sweet to eat or drink like a candy, sugar cubes, juice, or another high sugar snack.

Surgery

Transplantation of a healthy pancreas into a diabetic patient is a successful treatment, however, this transplant is usually done only if a kidney transplant is performed at the same time. Although a pancreas transplant is possible, it is not clear if the potential benefits outweigh the risks of the surgery and drug therapy needed.

Alternative treatment

Since diabetes can be life-threatening if not properly managed, patients should not attempt to treat this condition without medical supervision. A variety of alternative therapies can be helpful in managing the symptoms of diabetes and supporting patients with the disease. Acupuncture can help relieve the pain associated with diabetic neuropathy by stimulation of certain points. A qualified practitioner should be consulted. Herbal remedies also may be helpful in managing diabetes. Although there is no herbal substitute for insulin, some herbs may help adjust blood sugar levels or manage other diabetic symptoms. Some options include:

  • fenugreek (Trigonella foenum-graecum) has been shown in some studies to reduce blood insulin and glucose levels while also lowering cholesterol
  • bilberry (Vaccinium myrtillus) may lower blood glucose levels, as well as helping to maintain healthy blood vessels
  • garlic (Allium sativum) may lower blood sugar and cholesterol levels
  • onions (Allium cepa) may help lower blood glucose levels by freeing insulin to metabolize them
  • cayenne pepper (Capsicum frutescens) can help relieve pain in the peripheral nerves (a type of diabetic neuropathy)
  • gingko (Gingko biloba) may maintain blood flow to the retina, helping to prevent diabetic retinopathy

Any therapy that lowers stress levels also can be useful in treating diabetes by helping to reduce insulin requirements. Among the alternative treatments that aim to lower stress are hypnotherapy, biofeedback, and meditation.

Prognosis

Uncontrolled diabetes is a leading cause of blindness, end-stage renal disease, and limb amputations. It also doubles the risks of heart disease and increases the risk of stroke. Eye problems including cataracts, glaucoma, and diabetic retinopathy also are more common in diabetics.

Diabetic peripheral neuropathy is a condition where nerve endings, particularly in the legs and feet, become less sensitive. Diabetic foot ulcers are a particular problem since the patient does not feel the pain of a blister, callous, or other minor injury. Poor blood circulation in the legs and feet contribute to delayed wound healing. The inability to sense pain along with the complications of delayed wound healing can result in minor injuries, blisters, or callouses becoming infected and difficult to treat. In cases of severe infection, the infected tissue begins to break down and rot away. The most serious consequence of this condition is the need for amputation of toes, feet, or legs due to severe infection.

Heart disease and kidney disease are common complications of diabetes. Long-term complications may include the need for kidney dialysis or a kidney transplant due to kidney failure.

Babies born to diabetic mothers have an increased risk of birth defects and distress at birth.

Prevention

Research continues on diabetes prevention and improved detection of those at risk for developing diabetes. While the onset of Type I diabetes is unpredictable, the risk of developing Type II diabetes can be reduced by maintaining ideal weight and exercising regularly. The physical and emotional stress of surgery, illness, pregnancy, and alcoholism can increase the risks of diabetes, so maintaining a healthy lifestyle is critical to preventing the onset of Type II diabetes and preventing further complications of the disease.

Resources

PERIODICALS

Crutchfield, Diane B. “Oral Antidiabetic Agents: Back to the Basics.” Geriatric Times. May 1, 2003: 20.

“Gestational Diabetes Increases 35% in 10 Years.” Health & Medicine Week. March 22, 2004: 220.

Kordella, Terri. “New Combo Pills.” Diabetes Forecast. March 2003: 42.

“New Drugs.” Drug Topics. November 18, 2002: 73. “Research: Lower Chromium Levels Linked to Increased Risk of Disease.” Diabetes Week. March 29, 2004: 21.

“Standards of Medical Care for Patients with Diabetes Mellitus: American Diabetes Association.” Clinical Diabetes.

Winter 2003: 27. ldquo;Wider Metformin Use Recommended.” Chemist & Druggist. January 11, 2003: 24.

ORGANIZATIONS

American Diabetes Association. 1701 North Beauregard Street, Alexandria, VA 22311. (800) 342-2383. <http://www.diabetes.org.>

American Dietetic Association. 216 W. Jackson Blvd., Chicago, IL 60606-6995. (312) 899-0040. <http://www.eatright.org.>

Juvenile Diabetes Foundation. 120 Wall St., 19th Floor, New York, NY 10005. (800) 533-2873. <http://www.jdf.org.>

National Diabetes Information Clearinghouse. 1 Information Way, Bethesda, MD 20892-3560. (800) 860-8747. [email protected]. <http://www.niddk.nih.gov/health/diabetes/ndic.htm.>

OTHER

Centers for Disease Control. <http://www.cdc.gov/nccdphp/ddt/ddthome.htm>.

“Insulin-Dependent Diabetes.” National Institute of Diabetes and Digestive and Kidney Diseases. National Institutes of Health, NIH Publication No.94-2098.

“Noninsulin-Dependent Diabetes.” National Institute of Diabetesand Digestive and Kidney Diseases. National Institutes of Health, NIH Publication No.92-241.

Altha Roberts Edgren Teresa G. Odle.

Diarrhea see Traveler’s diarrhea.

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Diabetes mellitus

Definition

Diabetes mellitus is a condition that occurs when either the pancreas does not produce enough insulin or the body's cells stop responding to the insulin that is produced. In either case, glucose in the blood cannot be absorbed or used by the cells of the body.

Description

Diabetes has been recognized as a disease since ancient times. Egyptian papyri described its symptoms in 1550 b.c., and Hindu physicians noted 500 years later that insects were drawn to the sugary urine of people afflicted with diabetes. The disease was first named in 230 b.c. by Apollonius of Memphis, who took it from the Greek diabainein (to pass through), a description of the unquenchable thirst and copious urine produced by diabetics. It was not until the latter part of the eighteenth century that the British physician John Rollo appended the Latin term mellitus (honey-sweet) to distinguish diabetes from other diseases that caused excessive urine production.

Diabetes mellitus is a chronic disease that causes serious health complications including renal failure, heart disease, stroke, blindness, and peripheral neuropathy with vascular insufficiency, putting patients at risk for gangrene and subsequent amputation of the extremities. Approximately 16 million Americans have diabetes; of these, it is estimated that around 5.4 million are undiagnosed. Diabetes afflicts 120 million people worldwide, with the World Health Organization predicting that the number will reach 300 million by 2025.

Physiology

Every cell in the human body requires fuel to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates . Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. Insulin is a protein hormone secreted into the blood by cells in the pancreas called islets of Langerhans. Insulin bonds to a receptor site on the outside of a cell, and acts like a key to open a doorway into the cell through which glucose can enter. The liver may convert excess glucose to concentrated energy sources like glycogen or fatty acids, which are stored for later use. If there is insufficient insulin production, or when the doorway no longer recognizes the insulin key, glucose stays in the blood rather than entering the cells.

As the level of glucose in the blood rises, a condition called hyperglycemia results. The body will try to dilute this high blood glucose level by drawing water out of the cells, pumping it into the bloodstream, and excreting it in urine. It is not unusual for those with undiagnosed diabetes to complain of constant thirst, to drink large quantities of fluids, and to urinate frequently as their bodies attempt to get rid of the extra glucose.

At the same time that the body is attempting to rid itself of glucose in the blood, its cells are starving for glucose and sends signals to eat more food, giving patients tremendous appetites. To provide energy for the starving cells, the body also tries to convert fats and proteins into glucose. Breaking down these substances causes acid compounds called ketones to form in the blood and to be excreted in the urine. As ketones build up in the blood, a condition called ketoacidosis can occur. If left untreated, this condition can be life threatening, eventually leading to coma and death.

Types of diabetes mellitus

Type 1 diabetes, sometimes called juvenile diabetes, commonly begins in childhood or adolescence. It occurs more frequently in populations descended from northern European countries than in those from southern Europe, the Middle East, or Asia. This form of diabetes is also called insulin-dependent diabetes because people who develop it need to have insulin injections at least once a day. In this form of diabetes, the body produces little or no insulin. Its onset is sudden, and it usually–but not always—occurs in people under 30.

Brittle diabetics are a subgroup of type 1 in which patients have frequent and rapid blood sugar level swings, alternating between hyper-and hypoglycemia. These patients may need several injections of different types of insulin taken at specific times during the day to maintain a blood glucose level within a fairly normal range.

The more common form of diabetes is type 2, sometimes called age-onset or adult-onset diabetes. It accounts for more than 90% of all diabetes in the United States. This form occurs most often in people who are over 50, as well as those who are overweight and sedentary; it is also more common in people of Native American, Hispanic, and African-American descent. People who have migrated to Western cultures from East India, Japan, and Australian Aboriginal cultures are also more likely to develop type 2 diabetes than those who remain in their native countries.

Type 2, also called noninsulin-dependent diabetes, is considered a milder form of diabetes because of its gradual onset (sometimes developing over the course of several years) and because it can often be controlled with diet and oral medication. The consequences of uncontrolled and untreated type 2 diabetes, however, are as serious as those caused by type 1. Many people with type 2 diabetes are able to control their blood glucose with diet and oral medications, but for those who cannot, insulin injections may be necessary. In recent years, an alarming trend was being noted in Western culture, particularly in the United States: a tendency for children, teenagers, and young adults, particularly those who are obese, to develop this type of diabetes.

Another type of diabetes is gestational diabetes , which can develop during pregnancy and generally resolves after the delivery of the baby. This diabetic condition develops during the second or third trimester in approximately 2% of pregnancies. The condition is normally treated by diet, however, insulin injections may be required for periodic exacerbation control. Women who develop diabetes during pregnancy are at higher risk for developing type 2 diabetes within five to 10 years.

Diabetes may also develop as a result of or in concert with pancreatic disease, alcoholism , malnutrition, or other severe illnesses that tax the body's immune system .

Causes and symptoms

The causes of diabetes mellitus are unclear, however, there appear to be both hereditary and environmental factors involved. Research has shown that some people who develop diabetes have common genetic markers. In type 1 diabetes, the immune system is probably triggered by a virus or other microorganism that destroys the cells in the pancreas that produce insulin.

Type 2 diabetes is characterized by the insulin resistance syndrome, in which peripheral adipose and muscle cells fail to respond appropriately to circulating insulin, which the pancreas produces in response to food loads. Research has now shown that the insulin resistance syndrome is closely associated with dyslipidemia, an imbalance in the ratio of total cholesterol to the cholesterol fractions of either low-density lipoproteins (bad cholesterol) or to high-density lipoproteins (good cholesterol). Untreated or inadequately treated dyslipidemia leads to atherosclerosis and eventually to the microvascular complications mentioned above. Patients with type 2 diabetes and dyslipidemia are often treated with one of the drugs from the group known as statins, in addition to oral antidiabetic agents.

Age, obesity , and family history may all play a role in the development of type 2 diabetes. Symptoms may begin so gradually that a person may not be aware of them. Early signs are fatigue, extreme thirst, and frequent urination. Other symptoms may include sudden weight loss, slow wound healing, urinary tract infections, or blurred vision . It is not unusual for type 2 diabetes to be detected while a patient is seeing a doctor for another health concern that is actually being caused by the as-yetundiagnosed diabetes.

Individuals who are at high risk of developing type 2 diabetes mellitus include those who:

  • Are obese (more than 20% above their ideal body weight).
  • Have a primary relative (immediate family member) with diabetes mellitus.
  • Belong to a high-risk ethnic population (African American, Native American, Hispanic, or Native Hawaiian).
  • Have been diagnosed with gestational diabetes or have delivered a baby weighing more than 9 lbs (4 kg).
  • Have been diagnosed with transient diabetes at the time of a moderate to severe systemic infection (like protracted pneumonia).
  • Have high blood pressure (140/90 mm Hg or above).
  • Have a high-density lipoprotein cholesterol level less than or equal to 35 mg/dL and/or a triglyceride level greater than or equal to 250 mg/dL.
  • Have had impaired glucose tolerance or impaired fasting glucose on previous testing.

Several common medications can impair the body's use of insulin, causing a condition known as secondary diabetes. These medications include treatments for high blood pressure (furosemide, clonidine, and thiazide diuretics), drugs with hormonal activity (oral contraceptives, thyroid hormone, progestins, and systemic gluococorticoids), and the anti-inflammation drug indomethacin. Several drugs used to treat mood disorders can also impair glucose absorption. These drugs include haloperidol, lithium carbonate, phenothiazines, tricyclic antidepressants, and adrenergic agonists. Other medications that can cause diabetes symptoms include isoniazid, nicotinic acid, cimetidine, and heparin.

Symptoms

Symptoms of diabetes can develop suddenly (over days or weeks) in previously healthy children or adolescents, or can develop gradually (over several years) in overweight adults past the age of 40. The classic symptoms include fatigue, frequent urination, excessive thirst, excessive hunger, tingling of hands and feet, pruritus, and weight loss. In sudden-onset diabetes, some patients may have a "fruity" odor to their breath.

Ketoacidosis, a condition that results from starvation or uncontrolled diabetes, is common in patients with type 1 diabetes. Its symptoms include abdominal pain , vomiting, tachypnea, and extreme fatigue or lethargy. Patients with ketoacidosis will also have a characteristically sweet, fruity breath odor. Left untreated, this condition may lead to coma and death.

With type 2 diabetes, the condition may not become evident until the patient presents for medical treatment for some other condition. A patient may have heart disease, chronic infections of the gums and urinary tract, blurred vision, numbness in the feet and legs, and slowly healing wounds . Women may experience genital itching.

Diagnosis

Urine tests

Diabetes is suspected based on symptoms, but many of its symptoms may also suggest other diseases. Urine tests can begin the winnowing process that leads to a definitive diagnosis. Urine tests can detect ketones and protein in the urine; they can also show urine "spill," the renal threshold at which the kidneys will spill excess blood sugar into the urine. They can help assess how adequately the kidneys are functioning, and are used to monitor the disease once the patient is compliant with the recommended diet, oral medications, or insulin.

Blood tests

Although urine tests can confirm an initial suspicion of diabetes, specific blood tests are often required to make the differential diagnosis. One such diagnostic tool is the fasting glucose test. Blood is drawn via a venipuncture after a period of at least eight hours of fasting, usually in the morning prior to breakfast. The red blood cells are separated from the sample and the amount of glucose is measured in the remaining plasma. A plasma level of 7.8 mmol/L (200 mg/L) or greater can indicate diabetes. The fasting glucose test is usually repeated on another day to confirm the results. A postprandial glucose test involves taking blood one to two hours after the patient has eaten a meal.

A glucose tolerance involves blood and urine sampling over a three-or five-hour period after a patient drinks a specially prepared syrup of glucose and other sugars. During the test the patient drinks no other fluids. When patients are healthy, the blood glucose level rises immediately after the drink and then decreases gradually as insulin is used by the body to metabolize the glucose. In patients with diabetes, the serum glucose rises and stays elevated after drinking the sweetened liquid. A plasma glucose level of 11.1mmol/L (200 mg/dL) or higher two hours after drinking the syrup and at one other point during the two-hour test period confirms the diagnosis of diabetes. During this time, the urine is tested for glucose spill.

A diagnosis of diabetes is confirmed if there are symptoms of diabetes and a blood glucose level of at least 11.1 mmol/L, a fasting plasma glucose level of at least 7 mmol/L, or a two-hour plasma glucose level of at least 11.1 mmol/L during an oral glucose tolerance test.

Monitoring glucose levels

The blood test that gives the best indication of average blood glucose levels over time is the hemoglobin A1C (HbA1C) test. It measures the percentage of hemoglobin A that has become glycosylated (coated with glucose) during the past three months. (Red blood cells have a life span of about 100 days; after that they are recycled by the bone marrow.) A normal reading for healthy individuals is about of 4–6% glycosylated HbA1C. Diabetics whose disease is well controlled will read 7% or lower. A reading of 8% or higher indicates the need for a change in treatment or better dietary compliance; these patients are also at increased risk for such complications as eye disease, kidney disease, and nerve damage. The HbA1C test should be performed at least twice a year to be sure that blood glucose levels stay within safe and healthy levels.

Home blood glucose monitoring kits are available so patients with diabetes can monitor their daily glucose readings. For decades, a small needle or lancet was used to prick the finger and a drop of blood was collected and analyzed by a monitoring device. Modern blood monitoring devices, however, are strapped on like a wrist watch; no finger sticks are required. This is especially helpful for patients who need to test their blood glucose levels several times during the day.

Treatment

There is no cure for diabetes; it can, however, be controlled so that patients can live a relatively normal life. Treatment focuses on two goals: keeping blood glucose readings within a normal range (140 mg/dL, the standard accepted by the American Diabetes Association) and preventing the development of long-term complications. Careful monitoring of diet, exercise , and blood glucose levels are important, affecting the need for insulin replacement as well as the dose of oral antidiabetic agents. Lack of consistent control leads to complications of the disease.

Dietary changes

Diet and moderate exercise are the first treatments implemented in diabetes. For many type 2 diabetics, weight loss may be an especially important part of treatment. A well balanced, nutritious diet provides approximately 50% to 60% of calories from carbohydrates, around 10% to 20% from protein, and less than 30% of calories from fat. The number of calories required by an individual depends on their age, weight, and activity level. Calorie intake also needs to be distributed over the course of the entire day so that surges of glucose entering the blood are kept to a minimum. The timing of snacks must also correspond to the timing and type of insulin being used.

Counting the calories in different foods can be complicated, so patients are usually advised to consult a nutritionist, who will set up an individualized, easily managed diet for each patient. Both the American Diabetes Association and the American Dietetic Association recommend diets based on the use of food-exchange lists. Each food-exchange unit contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient's diet plan will allow a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at mealtimes and as snacks. Patients can choose which foods they eat as long as they stick with the number of exchanges prescribed and adhere to their schedule if they take a combination of insulin types. The food exchange system, along with an exercise program, can help patients lose excess weight and improve their overall health. This may be especially important for type 2 diabetics.

Oral medications

A variety of oral medications are available to help lower blood glucose in type 2 diabetics. They act in a variety ways to control postprandial (after meal) glucose levels; the particular medication or combination of drugs chosen will be based largely on the individual patient profile. Some oral medications stimulate the pancreatic beta cells to produce additional insulin. Others change the way receptors on peripheral adipose (fat) and muscle cells receive the insulin and act on it, and still others block the intestinal absorption of food byproducts that would increase blood glucose levels.

All drugs have side effects that may make them inappropriate for particular patients. For example, some medications may stimulate weight gain or cause stomach irritation, so they may not be the best treatment for individuals who are already overweight or who have stomach ulcers. While these medications are an important aspect of treatment for type 2 diabetes, they are not a substitute for an appropriate diet and exercise. Oral medications are not effective for type 1 diabetes, in which the patient produces little or no insulin.

Insulin

Patients with type 1 diabetes need daily injections of insulin to help their bodies utilize glucose. The amount and type of insulin required depends on the individual patient's height, weight, age, food intake (quantity and timing), and activity level. Some patients with type 2 diabetes may need to use insulin injections if their diabetes cannot be controlled with diet, exercise, and oral medication. Injections are given subcutaneously, using a small needle and syringe. Injection sites can be anywhere on the body where there is adequate subcutaneous tissue, including the upper arm, abdomen, hips, or upper thigh.

Purified human insulin is most commonly used, however, insulin from beef and pork sources is also available. Insulin may be given as an injection of a single dose of one type of insulin once a day. Different types of insulin (short-acting rapid-onset, slow-onset long-acting) can be mixed and given in one dose or split into two or more doses during the day. Patients that require multiple injections over the course of a day may be able to use an insulin pump that administers small doses of insulin on demand. The small battery-operated pump is worn outside the body and is connected to a tube that is inserted into the abdomen. Pumps can be programmed to inject small doses of insulin at various times during the day, or the patient may be able to adjust the insulin doses to coincide with glucometer readings, meals, and exercise. There are also multiple-dose insulin injection devices available that are commonly referred to as insulin pens. They are designed to hold a cartridge containing several days' worth of insulin dosages.

Regular human insulin is fast-acting and begins to work within 15–30 minutes; its peak glucose-lowering effect occurs about two hours later and its effects last approximately 4–6 hours. Neutral protamine Hagedorn (NPH) and Lente insulin are intermediate-acting insulins that start to work within 4–8 hours, and last 18–26 hours. Ultralente is a long-acting form of insulin that starts to work within four to eight hours and lasts 28 to 36 hours. Many diabetics combine a long-or intermediate acting insulin with a short-acting one to provide the proper insulin peak at mealtimes. Premixed insulins are available in standard doses. Newer forms of insulin are under investigation.

Although the goal of most diabetes treatment is to lower blood glucose levels, hypoglycemia, or low blood glucose, can be caused by too much insulin, too little food, alcohol consumption, or increased exercise. A patient with symptoms of hypoglycemia may be hungry, irritable, confused, and tired. The patient may be diaphoretic (sweating profusely), pale, and shaky. Left untreated, the patient can lose consciousness or have a seizure soon after these symptoms appear. This condition, called an insulin reaction or insulin shock, should be treated by giving the conscious patient something with readily available sugar to eat or drink like orange juice, hard candy, or sugar cubes. If the patient has declined into unconsciousness, do not try to feed them. This is a critical condition and always requires emergency intravenous therapy.

Surgery

Transplantation of healthy pancreatic tissue into a diabetic patient can be successful. However, it is not clear if the potential benefits outweigh the risks of the surgery and drug therapy required.

Alternative therapies

Since uncontrolled diabetes can be life-threatening if not properly managed, patients should be instructed to not attempt treatments without medical supervision. Patients interested in alternative and herbal remedies should be instructed about the possible benefits, but cautioned to consult with a health care professional before they try them. Some alternative therapies may interact negatively with some of the oral antidiabetic agents or other drugs, such as antihypertensives or anticoagulants.


KEY TERMS


Diabetic peripheral neuropathy —Condition in which the sensitivity of nerves to pain, temperature, and pressure is dulled, particularly in the legs and feet.

Diabetic retinopathy —A condition in which the tiny blood vessels to the retina are damaged, leading to blurred vision, sudden blindness, or black spots, lines, or flashing light in the field of vision.

Hemoglobin A —Normal hemoglobin found in the blood of an adult.

Hemoglobin A1C —One of three fractions of hemoglobin A; the other two are HBA1a and HbA1b. Because HbA1c can become glycosylated, it is an important measure of blood glucose over the past three months.

Hyperglycemia —Abnormally high levels of blood glucose.

Hypoglycemia —Abnormally low levels of blood glucose.

Ketoacidosis —Condition that results in untreated diabetes from the body's attempt to burn fat for fuel when carbohydrates cannot be utilized. Ketones, the byproduct of fat metabolism, enter the bloodstream and make the blood more acidic than the body's tissues.

Pruritus —Itching.

Tachypnea —Rapid breathing.


For patients who are willing to consult with their physician, alternative options may include:

  • Fenugreek has been shown in some studies to reduce blood insulin and glucose levels while also lowering cholesterol.
  • Bilberry may lower blood glucose levels, as well as help to maintain healthy blood vessels .
  • Garlic may lower blood sugar and cholesterol levels.
  • Cayenne pepper may help relieve the pain of diabetic neuropathy.

Any therapy that lowers stress levels may also be useful in treating diabetes by helping to reduce insulin requirements. Among the alternative treatments that aim to lower stress are hypnotherapy, biofeedback, and meditation .

Prognosis

Uncontrolled diabetes is a leading cause of blindness, end-stage renal disease, and peripheral vascular insufficiency, which leads to limb amputations. It also doubles the risks of heart disease and increases the risk of stroke. Eye problems including cataracts , glaucoma , and diabetic retinopathy are also more common in diabetics.

Diabetic peripheral neuropathy is a condition where nerve endings, particularly in the legs and feet, become less sensitive. Diabetic foot ulcers are a particular problem since the patient does not feel the pain of a blister, callous, or other minor injury. Poor blood circulation in the legs and feet contribute to delayed wound healing. The inability to sense pain along with the complications of delayed wound healing can cause minor injuries, blisters, or calluses to become infected and difficult to treat. In cases of severe infection, the infected tissue begins to break down and rot away. The severe infection may further exacerbate diabetes and increase blood glucose levels, perpetuating the problem. In the most serious infection cases, toes, feet, or legs may need to be amputated.

Diabetes can also affect the kidneys, a condition called diabetic nephropathy. This usually means that soft kidney tissue hardens and thickens, a process called sclerosis; this is especially true for the glomerulus (kidney membrane), which filters protein and other waste products from the blood. The ADA estimates that 35–45% of type 1 patients and 20–30% of type 2 patients have damaged kidneys. Because the symptoms of nephropathy may not appear until 80% of kidney function is gone, periodic tests of kidney function are especially important for patients with diabetes. Once renal function drops to 10–15%, kidney dialysis or a kidney transplant become necessary.

The risk of heart disease for patients with diabetes is two to four times higher than that of the general population. Death from heart disease is also two to four time higher in diabetics, as is the risk of stroke. These statistics hold for people with both type 1 and type 2 diabetes. The risk of cardiovascular disease increases with age, obesity, smoking, poor blood glucose control, and family history of heart disease.

Health care team roles

All members of the health care team may come into contact with diabetic patients. The nurse plays a particularly important role in teaching patients the skills necessary to manage this complex disease, and educating them about the effects of their medications.

Prevention

Research continues on ways to prevent diabetes and to detect those at risk for developing the disease. While the onset of type 1 diabetes is unpredictable, the risks for developing type 2 diabetes can be reduced by maintaining a healthy weight and exercising regularly. The physical and emotional stresses of surgery, illness (especially systemic infection), pregnancy, and alcoholism can all increase the risks for diabetes, so maintaining a healthy lifestyle is critical to preventing the onset of type 2 diabetes and further complications. Research is in progress to determine the usefulness of placing high-risk patients on metformin (Glucophage; an oral antidiabetic drug used to treat type 2 diabetes) prophylactically in an effort to delay or prevent the onset of type 2 diabetes.

Resources

BOOKS

Beers, Mark H., and Robert Berkow. The Merck Manual of Diagnosis and Therapy. 17th ed. Whitehouse Station, NJ: Merck and Company, Inc., 1999.

PERIODICALS

Lincoln, Thomas A. "A1c: Know Your Value!" Diabetes Forecast (March 2001): 66.

Pennachio, Dorothy L. "How to Manage Diabetes in the Older Patient." Patient Care (January 30, 2001): 53.

ORGANIZATIONS

American Diabetes Association. 1701 North Beauregard Street, Alexandria, VA 22311. 800-DIABETES. <http://www.diabetes.org>.

Juvenile Diabetes Foundation International. 120 Wall Street, New York, NY 10005-4001. 800-JDF-CURE. <http://www.jdf.org>.

OTHER

American Diabetes Association. Clinical Practice Recommendatons. "Tests of Glycemia in Diabetes" Position Statement. Diabetes Care 24, no. 1. <http://journal.diabetes.org/FullText/Supplements/DiabetesCare/Supplement101/S80.htm>.

Diabetes Manager. "History of Diabetes." <http://www.diabetesmanager.com/Education/Articles/Basics/history.html>.

Kentucky Department for Public Health. "The Hemoglobin A1C Test: The Best Test For Blood Sugar Control." <http://publichealth.state.ky.us/diabetes-hemoglobin_a1c_test.htm>.

Moran, David T. "Glycosylated hemoglobin." <http://www.healthanswers.com/library/MedEnc/enc/1273.asp>.

Deanna M. Swartout-Corbeil, R.N.

views updated

Diabetes Mellitus

Definition

Diabetes mellitus is a condition that occurs when either the pancreas does not produce enough insulin or the body's cells stop responding to the insulin that is produced. In either case, glucose in the blood cannot be absorbed or used by the cells of the body.

Description

Diabetes has been recognized as a disease since ancient times. Egyptian papyri described its symptoms in 1550 b.c.e., and Hindu physicians noted 500 years later that insects were drawn to the sugary urine of people afflicted with diabetes. The disease was first named in 230 b.c.e. by Apollonius of Memphis, who took it from the Greek diabainein (to pass through), a description of the unquenchable thirst and copious urine produced by diabetics. It was not until the latter part of the eighteenth century that the British physician John Rollo appended the Latin term mellitus (honey-sweet) to distinguish diabetes from other diseases that caused excessive urine production.

Diabetes mellitus is a chronic disease that causes serious health complications including renal failure, heart disease, stroke, blindness, and peripheral neuropathy with vascular insufficiency, putting patients at risk for gangrene and subsequent amputation of the extremities. Approximately 16 million Americans have diabetes; of these, it is estimated that around 5.4 million are undiagnosed. Diabetes afflicts 120 million people worldwide, with the World Health Organization predicting that the number will reach 300 million by 2025.

Physiology

Every cell in the human body requires fuel to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates. Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. Insulin is a protein hormone secreted into the blood by cells in the pancreas called islets of Langerhans. Insulin bonds to a receptor site on the outside of a cell, and acts like a key to open a doorway into the cell through which glucose can enter. The liver may convert excess glucose to concentrated energy sources like glycogen or fatty acids, which are stored for later use. If there is insufficient insulin production, or when the doorway no longer recognizes the insulin key, glucose stays in the blood rather than entering the cells.

As the level of glucose in the blood rises, a condition called hyperglycemia results. The body will try to dilute this high blood glucose level by drawing water out of the cells, pumping it into the bloodstream, and excreting it in urine. It is not unusual for those with undiagnosed diabetes to complain of constant thirst, to drink large quantities of fluids, and to urinate frequently as their bodies attempt to get rid of the extra glucose.

At the same time that the body is attempting to rid itself of glucose in the blood, its cells are starving for glucose and sends signals to eat more food, giving patients tremendous appetites. To provide energy for the starving cells, the body also tries to convert fats and proteins into glucose. Breaking down these substances causes acid compounds called ketones to form in the blood and to be excreted in the urine. As ketones build up in the blood, a condition called ketoacidosis can occur. If left untreated, this condition can be life threatening, eventually leading to coma and death.

Types of diabetes mellitus

Type 1 diabetes, sometimes called juvenile diabetes, commonly begins in childhood or adolescence. It occurs more frequently in populations descended from northern European countries than in those from southern Europe, the Middle East, or Asia. This form of diabetes is also called insulin-dependent diabetes because people who develop it need to have insulin injections at least once a day. In this form of diabetes, the body produces little or no insulin. Its onset is sudden and usually occurs in people under 30.

Brittle diabetics are a subgroup of type 1 in which patients have frequent and rapid blood sugar level swings, alternating between hyper-and hypoglycemia. These patients may need several injections of different types of insulin taken at specific times during the day to maintain a blood glucose level within a fairly normal range.

The more common form of diabetes is type 2, sometimes called age-onset or adult-onset diabetes. It accounts for more than 90% of all diabetes in the United States. This form occurs most often in people who are over 50, as well as those who are overweight and sedentary; it is also more common in people of Native American, Hispanic, and African-American descent. People who have migrated to Western cultures from East India, Japan, and Australian Aboriginal cultures are also more likely to develop type 2 diabetes than those who remain in their native countries.

Type 2, also called noninsulin-dependent diabetes, is considered a milder form of diabetes because of its gradual onset (sometimes developing over the course of several years) and because it can often be controlled with diet and oral medication. The consequences of uncontrolled and untreated type 2 diabetes, however, are as serious as those caused by type 1. Many people with type 2 diabetes are able to control their blood glucose with diet and oral medications, but for those who cannot, insulin injections may be necessary. In recent years, an alarming trend was being noted in Western culture, particularly in the United States: a tendency for children, teenagers, and young adults, particularly those who are obese, to develop this type of diabetes.

Another type of diabetes is gestational diabetes, which can develop during pregnancy and generally resolves after the delivery of the baby. This diabetic condition develops during the second or third trimester in approximately 2% of pregnancies. The condition is normally treated by diet, however, insulin injections may be required for periodic exacerbation control. Women who develop diabetes during pregnancy are at higher risk for developing type 2 diabetes within five to 10 years.

Diabetes may also develop as a result of or in concert with pancreatic disease, alcoholism, malnutrition, or other severe illnesses that tax the body's immune system.

Causes and symptoms

The causes of diabetes mellitus are unclear, however, there appear to be both hereditary and environmental factors involved. Research has shown that some people who develop diabetes have common genetic markers. In type 1 diabetes, the immune system is probably triggered by a virus or other microorganism that destroys the cells in the pancreas that produce insulin.

Type 2 diabetes is characterized by the insulin resistance syndrome, in which peripheral adipose and muscle cells fail to respond appropriately to circulating insulin, which the pancreas produces in response to food loads. Research has now shown that the insulin resistance syndrome is closely associated with dyslipidemia, an imbalance in the ratio of total cholesterol to the cholesterol fractions of either low-density lipoproteins (bad cholesterol) or to high-density lipoproteins (good cholesterol). Untreated or inadequately treated dyslipidemia leads to atherosclerosis and eventually to the microvascular complications mentioned above. Patients with type 2 diabetes and dyslipidemia are often treated with one of the drugs from the group known as statins, in addition to oral antidiabetic agents.

Age, obesity, and family history may all play a role in the development of type 2 diabetes. Symptoms may begin so gradually that a person may not be aware of them. Early signs are fatigue, extreme thirst, and frequent urination. Other symptoms may include sudden weight loss, slow wound healing, urinary tract infections, or blurred vision. It is not unusual for type 2 diabetes to be detected while a patient is seeing a doctor for another health concern that is actually being caused by the as-yet-undiagnosed diabetes.

Individuals who are at high risk of developing type 2 diabetes mellitus include those who:

  • Are obese (more than 20% above their ideal body weight).
  • Have a primary relative (immediate family member) with diabetes mellitus.
  • Belong to a high-risk ethnic population (African American, Native American, Hispanic, or Native Hawaiian).
  • Have been diagnosed with gestational diabetes or have delivered a baby weighing more than 9 lbs (4 kg).
  • Have been diagnosed with transient diabetes at the time of a moderate to severe systemic infection (like protracted pneumonia).
  • Have high blood pressure (140/90 mmHg or above). Have a high-density lipoprotein cholesterol level less than or equal to 35 mg/dL and/or a triglyceride level greater than or equal to 250 mg/dL.
  • Have had impaired glucose tolerance or impaired fasting glucose on previous testing.

Several common medications can impair the body's use of insulin, causing a condition known as secondary diabetes. These medications include treatments for high blood pressure (furosemide, clonidine, and thiazide diuretics), drugs with hormonal activity (oral contraceptives, thyroid hormone, progestins, and systemic gluococorticoids), and the anti-inflammation drug indomethacin. Several drugs used to treat mood disorders can also impair glucose absorption. These drugs include haloperidol, lithium carbonate, phenothiazines, tricyclic antidepressants, and adrenergic agonists. Other medications that can cause diabetes symptoms include isoniazid, nicotinic acid, cimetidine, and heparin.

Symptoms

Symptoms of diabetes can develop suddenly (over days or weeks) in previously healthy children or adolescents, or can develop gradually (over several years) in overweight adults past the age of 40. The classic symptoms include fatigue, frequent urination, excessive thirst, excessive hunger, tingling of hands and feet, pruritus, and weight loss. In sudden-onset diabetes, some patients may have a "fruity" odor to their breath.

Ketoacidosis, a condition that results from starvation or uncontrolled diabetes, is common in patients with type 1 diabetes. Its symptoms include abdominal pain, vomiting, tachypnea, and extreme fatigue or lethargy. Patients with ketoacidosis will also have a characteristically sweet, fruity breath odor. Left untreated, this condition may lead to coma and death.

With type 2 diabetes, the condition may not become evident until the patient presents for medical treatment for some other condition. A patient may have heart disease, chronic infections of the gums and urinary tract, blurred vision, numbness in the feet and legs, and slowly healing wounds. Women may experience genital itching.

Diagnosis

Urine tests

Diabetes is suspected based on symptoms, but many of its symptoms may also suggest other diseases. Urine tests can begin the winnowing process that leads to a definitive diagnosis. Urine tests can detect ketones and protein in the urine; they can also show urine "spill," the renal threshold at which the kidneys will spill excess blood sugar into the urine. They can help assess how adequately the kidneys are functioning, and are used to monitor the disease once the patient is compliant with the recommended diet, oral medications, or insulin.

Blood tests

Although urine tests can confirm an initial suspicion of diabetes, specific blood tests are often required to make the differential diagnosis. One such diagnostic tool is the fasting glucose test. Blood is drawn via a venipuncture after a period of at least eight hours of fasting, usually in the morning prior to breakfast. The red blood cells are separated from the sample and the amount of glucose is measured in the remaining plasma. A plasma level of 7.8 mmol/L (200 mg/L) or greater can indicate diabetes. The fasting glucose test is usually repeated on another day to confirm the results. A postprandial glucose test involves taking blood one to two hours after the patient has eaten a meal.

A glucose tolerance involves blood and urine sampling over a three- or five-hour period after a patient drinks a specially prepared syrup of glucose and other sugars. During the test the patient drinks no other fluids. When patients are healthy, the blood glucose level rises immediately after the drink and then decreases gradually as insulin is used by the body to metabolize the glucose. In patients with diabetes, the serum glucose rises and stays elevated after drinking the sweetened liquid. A plasma glucose level of 11.1 mmol/L (200 mg/dL) or higher two hours after drinking the syrup and at one other point during the two-hour test period confirms the diagnosis of diabetes. During this time, the urine is tested for glucose spill.

A diagnosis of diabetes is confirmed if there are symptoms of diabetes and a blood glucose level of at least 11.1 mmol/L, a fasting plasma glucose level of at least 7 mmol/L, or a two-hour plasma glucose level of at least 11.1 mmol/L during an oral glucose tolerance test.

Monitoring glucose levels

The blood test that gives the best indication of average blood glucose levels over time is the hemoglobin A1C (HbA1C) test. It measures the percentage of hemoglobin A that has become glycosylated (coated with glucose) during the past three months. (Red blood cells have a life span of about 100 days; after that they are recycled by the bone marrow.) A normal reading for healthy individuals is about of 4-6% glycosylated HbA1C. Diabetics whose disease is well controlled will read 7% or lower. A reading of 8% or higher indicates the need for a change in treatment or better dietary compliance; these patients are also at increased risk for such complications as eye disease, kidney disease, and nerve damage. The HbA1C test should be performed at least twice a year to be sure that blood glucose levels stay within safe and healthy levels.

Home blood glucose monitoring kits are available so patients with diabetes can monitor their daily glucose readings. For decades, a small needle or lancet was used to prick the finger and a drop of blood was collected and analyzed by a monitoring device. Modern blood monitoring devices, however, are strapped on like a wrist watch; no finger sticks are required. This is especially helpful for patients who need to test their blood glucose levels several times during the day.

Treatment

There is no cure for diabetes; it can, however, be controlled so that patients can live a relatively normal life. Treatment focuses on two goals: keeping blood glucose readings within a normal range (140 mg/dL, the standard accepted by the American Diabetes Association) and preventing the development of long-term complications. Careful monitoring of diet, exercise, and blood glucose levels are important, affecting the need for insulin replacement as well as the dose of oral antidiabetic agents. Lack of consistent control leads to complications of the disease.

Dietary changes

Diet and moderate exercise are the first treatments implemented in diabetes. For many type 2 diabetics, weight loss may be an especially important part of treatment. A well balanced, nutritious diet provides approximately 50% to 60% of calories from carbohydrates, around 10% to 20% from protein, and less than 30% of calories from fat. The number of calories required by an individual depends on their age, weight, and activity level. Calorie intake also needs to be distributed over the course of the entire day so that surges of glucose entering the blood are kept to a minimum. The timing of snacks must also correspond to the timing and type of insulin being used.

Counting the calories in different foods can be complicated, so patients are usually advised to consult a nutritionist, who will set up an individualized, easily managed diet for each patient. Both the American Diabetes Association and the American Dietetic Association recommend diets based on the use of food-exchange lists. Each food-exchange unit contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient's diet plan will allow a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at mealtimes and as snacks. Patients can choose which foods they eat as long as they stick with the number of exchanges prescribed and adhere to their schedule if they take a combination of insulin types. The food exchange system, along with an exercise program, can help patients lose excess weight and improve their overall health. This may be especially important for type 2 diabetics.

Oral medications

A variety of oral medications are available to help lower blood glucose in type 2 diabetics. They act in a variety ways to control postprandial (after-meal) glucose levels; the particular medication or combination of drugs chosen will be based largely on the individual patient profile. Some oral medications stimulate the pancreatic beta cells to produce additional insulin. Others change the way receptors on peripheral adipose (fat) and muscle cells receive the insulin and act on it, and still others block the intestinal absorption of food byproducts that would increase blood glucose levels.

All drugs have side effects that may make them inappropriate for particular patients. For example, some medications may stimulate weight gain or cause stomach irritation, so they may not be the best treatment for individuals who are already overweight or who have stomach ulcers. While these medications are an important aspect of treatment for type 2 diabetes, they are not a substitute for an appropriate diet and exercise. Oral medications are not effective for type 1 diabetes, in which the patient produces little or no insulin.

Insulin

Patients with type 1 diabetes need daily injections of insulin to help their bodies utilize glucose. The amount and type of insulin required depends on the individual patient's height, weight, age, food intake (quantity and timing), and activity level. Some patients with type 2 diabetes may need to use insulin injections if their diabetes cannot be controlled with diet, exercise, and oral medication. Injections are given subcutaneously, using a small needle and syringe. Injection sites can be anywhere on the body where there is adequate subcutaneous tissue, including the upper arm, abdomen, hips, or upper thigh.

Purified human insulin is most commonly used, however, insulin from beef and pork sources is also available. Insulin may be given as an injection of a single dose of one type of insulin once a day. Different types of insulin (short-acting rapid-onset, slow-onset long-acting) can be mixed and given in one dose or split into two or more doses during the day. Patients that require multiple injections over the course of a day may be able to use an insulin pump that administers small doses of insulin on demand. The small battery-operated pump is worn outside the body and is connected to a tube that is inserted into the abdomen. Pumps can be programmed to inject small doses of insulin at various times during the day, or the patient may be able to adjust the insulin doses to coincide with glucometer readings, meals, and exercise. There are also multiple-dose insulin injection devices available that are commonly referred to as insulin pens. They are designed to hold a cartridge containing several days' worth of insulin dosages.

Regular human insulin is fast-acting and begins to work within 15 to 30 minutes; its peak glucose-lowering effect occurs about two hours later and its effects last approximately four to six hours. Neutral protamine Hagedorn (NPH) and Lente insulin are intermediateacting insulins that start to work within four to eight hours, and last 18 to 26 hours. Ultralente is a long-acting form of insulin that starts to work within four to eight hours and lasts 28 to 36 hours. Many diabetics combine a long-or intermediate acting insulin with a short-acting one to provide the proper insulin peak at mealtimes. Premixed insulins are available in standard doses. Newer forms of insulin are under investigation.

Although the goal of most diabetes treatment is to lower blood glucose levels, hypoglycemia, or low blood glucose, can be caused by too much insulin, too little food, alcohol consumption, or increased exercise. A patient with symptoms of hypoglycemia may be hungry, irritable, confused, and tired. The patient may be diaphoretic (sweating profusely), pale, and shaky. Left untreated, the patient can lose consciousness or have a seizure soon after these symptoms appear. This condition, called an insulin reaction or insulin shock, should be treated by giving the conscious patient something with readily available sugar to eat or drink like orange juice, hard candy, or sugar cubes. If the patient has declined into unconsciousness, do not try to feed them. This is a critical condition and always requires emergency intravenous therapy.

Surgery

Transplantation of healthy pancreatic tissue into a diabetic patient can be successful. However, it is not clear if the potential benefits outweigh the risks of the surgery and drug therapy required.

Alternative therapies

Since uncontrolled diabetes can be life-threatening if not properly managed, patients should be instructed to not attempt treatments without medical supervision. Patients interested in alternative and herbal remedies should be instructed about the possible benefits, but cautioned to consult with a health care professional before they try them. Some alternative therapies may interact negatively with some of the oral antidiabetic agents or other drugs, such as antihypertensives or anticoagulants. For patients who are willing to consult with their physician, alternative options may include:

  • Fenugreek has been shown in some studies to reduce blood insulin and glucose levels while also lowering cholesterol.
  • Bilberry may lower blood glucose levels, as well as help to maintain healthy blood vessels.
  • Garlic may lower blood sugar and cholesterol levels.
  • Cayenne pepper may help relieve the pain of diabetic neuropathy.

Any therapy that lowers stress levels may also be useful in treating diabetes by helping to reduce insulin requirements. Among the alternative treatments that aim to lower stress are hypnotherapy, biofeedback, and meditation.

Prognosis

Uncontrolled diabetes is a leading cause of blindness, end-stage renal disease, and peripheral vascular insufficiency, which leads to limb amputations. It also doubles the risks of heart disease and increases the risk of stroke. Eye problems including cataracts, glaucoma, and diabetic retinopathy are also more common in diabetics.

Diabetic peripheral neuropathy is a condition where nerve endings, particularly in the legs and feet, become less sensitive. Diabetic foot ulcers are a particular problem since the patient does not feel the pain of a blister, callous, or other minor injury. Poor blood circulation in the legs and feet contribute to delayed wound healing. The inability to sense pain along with the complications of delayed wound healing can cause minor injuries, blisters, or calluses to become infected and difficult to treat. In cases of severe infection, the infected tissue begins to break down and rot away. The severe infection may further exacerbate diabetes and increase blood glucose levels, perpetuating the problem. In the most serious infection cases, toes, feet, or legs may need to be amputated.

Diabetes can also affect the kidneys, a condition called diabetic nephropathy. This usually means that soft kidney tissue hardens and thickens, a process called sclerosis; this is especially true for the glomerulus (kidney membrane), which filters protein and other waste products from the blood. The ADA estimates that 35-45% of type 1 patients and 20-30% of type 2 patients have damaged kidneys. Because the symptoms of nephropathy may not appear until 80% of kidney function is gone, periodic tests of kidney function are especially important for patients with diabetes. Once renal function drops to 10-15%, kidney dialysis or a kidney transplant become necessary.

The risk of heart disease for patients with diabetes is two to four times higher than that of the general population. Death from heart disease is also two to four time higher in diabetics, as is the risk of stroke. These statistics hold for people with both type 1 and type 2 diabetes. The risk of cardiovascular disease increases with age, obesity, smoking, poor blood glucose control, and family history of heart disease.

KEY TERMS

Diabetic peripheral neuropathy— Condition in which the sensitivity of nerves to pain, temperature, and pressure is dulled, particularly in the legs and feet.

Diabetic retinopathy— A condition in which the tiny blood vessels to the retina are damaged, leading to blurred vision, sudden blindness, or black spots, lines, or flashing light in the field of vision.

Hemoglobin A— Normal hemoglobin found in the blood of an adult.

Hemoglobin A1C— One of three fractions of hemoglobin A; the other two are HBA1a and HbA1b. Because HbA1c can become glycosylated, it is an important measure of blood glucose over the past three months.

Hyperglycemia— Abnormally high levels of blood glucose.

Hypoglycemia— Abnormally low levels of blood glucose.

Ketoacidosis— Condition that results in untreated diabetes from the body's attempt to burn fat for fuel when carbohydrates cannot be utilized. Ketones, the byproduct of fat metabolism, enter the bloodstream and make the blood more acidic than the body's tissues.

Pruritus— Itching.

Tachypnea— Rapid breathing.

Health care team roles

All members of the health care team may come into contact with diabetic patients. The nurse plays a particularly important role in teaching patients the skills necessary to manage this complex disease, and educating them about the effects of their medications.

Prevention

Research continues on ways to prevent diabetes and to detect those at risk for developing the disease. While the onset of type 1 diabetes is unpredictable, the risks for developing type 2 diabetes can be reduced by maintaining a healthy weight and exercising regularly. The physical and emotional stresses of surgery, illness (especially systemic infection), pregnancy, and alcoholism can all increase the risks for diabetes, so maintaining a healthy lifestyle is critical to preventing the onset of type 2 diabetes and further complications. Research is in progress to determine the usefulness of placing high-risk patients on metformin (Glucophage; an oral antidiabetic drug used to treat type 2 diabetes) prophylactically in an effort to delay or prevent the onset of type 2 diabetes.

Resources

BOOKS

Beers, Mark H., and Robert Berkow. The Merck Manual of Diagnosis and Therapy, 17th ed. Whitehouse Station, NJ: Merck and Company, Inc., 1999.

PERIODICALS

Lincoln, Thomas A. "A1c: Know Your Value!" Diabetes Forecast (March 2001): 66.

Pennachio, Dorothy L. "How to Manage Diabetes in the Older Patient." Patient Care (January 30, 2001): 53.

ORGANIZATIONS

American Diabetes Association. 1701 North Beauregard Street, Alexandria, VA 22311. 800-DIABETES. 〈http://www.diabetes.org〉.

Juvenile Diabetes Foundation International. 120 Wall Street, New York, NY 10005-4001. 800-JDF-CURE. 〈http://www.jdf.org〉.

OTHER

American Diabetes Association. Clinical Practice Recommendatons. "Tests of Glycemia in Diabetes" Position Statement. Diabetes Care 24, no. 1. 〈http://journal.diabetes.org/FullText/Supplements/DiabetesCare/Supplement101/S80.htm〉.

Diabetes Manager. "History of Diabetes." 〈http://www.diabetesmanager.com/Education/Articles/Basics/history.html〉.

Kentucky Department for Public Health. "The Hemoglobin A1C Test: The Best Test For Blood Sugar Control." 〈http://publichealth.state.ky.us/diabeteshemoglobin_a1c_test.htm〉.

Moran, David T. "Glycosylated hemoglobin." 〈http://www.healthanswers.com/library/MedEnc/enc/1273.asp〉.

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Diabetes Mellitus

History of diabetes

Incidence of diabetes

Types of diabetes

Pre-diabetes

Tests for diabetes

Treatment for diabetes

Resources

Diabetes mellitus, what is informally called diabetes, is a group of diseases characterized by high levels of glucose in the blood resulting from defects in insulin production (insulin deficiency), insulin action (insulin resistance), or both. Insulin is a hormone produced by the pancreas. When eaten, foods are converted to a type of sugar called glucose that enters the bloodstream. Insulin is needed to move glucose into the body cells where it is used for energy, and excesses are stored in the liver and fat cells. Insufficient amounts of working insulin cause blood sugar levels to rise and large amounts of glucose are excreted in the urine. Consistently high levels of glucose in the bloodstream damage the nerves and blood vessels, and can lead to heart disease, stroke, high blood pressure, blindness, kidney disease, amputations, and dental disease.

The exact cause of diabetes is unknown, although genetics and environmental factors such as obesity and lack of exercise appear to play roles. Diabetes can be associated with serious complications and death, but people with diabetes can take an active role in controlling the disease and lowering the risk of complications.

History of diabetes

The history of diabetes mellitus dates back to ancient Egypt, where its symptoms were described around 2000 BC. The Greeks later gave the disease its name in the first century AD. The word diabetes means siphon, which describes a major symptom of the condition, frequent urination. Mellitus means honey, and depicts one of the early signs of diabetes, sugar in the urine.

Incidence of diabetes

Over 18 million people in the United States had diabetes as of 2005, or about 7% of the population. About one-third of diabetes victims are unaware that they have the disease. Higher rates of diabetes occur in certain populations: 13% of African Americans, 10.2% of Latino Americans, and 15.1% of Native Americans has diabetes. Prevalence of diabetes increases with age. Approximately 176, 500 people less than 20 years of age have diabetes (which is about one in every 400 to 600 children and adolescents [about 0.2%]), but about 9.6% of all people age 20 years or older has diabetes and approximately 20.9% of all people age 60 and older has diabetes. In the United States, 8.8% of all women and 10.5% of all men have diabetes. Over 1.5 million people over the age of 20 years are newly diagnosed with diabetes each year. Over 450, 000 deaths each year in the United States are attributed to diabetes.

Types of diabetes

There are three major types of diabetes: type 1, type 2, and gestational diabetes. Type 1 diabetes was previously called insulin-dependent diabetes or juvenile-onset diabetes. Type 1 diabetes develops when the bodys immune system destroys pancreatic beta cells, the only cells that produce insulin. The body, in turn, produces little or no insulin, resulting in insulin deficiency. Without insulin, the body is unable to use glucose for energy and begins to break down fats for fuel. Ketones are formed when fat is burned for energy. Excess ketones build up in the blood and lower the blood pH value leading to ketoacidosis.

Symptoms of type 1 diabetes usually appear suddenly and include increased thirst, frequent urination, increased hunger, tiredness, and weight loss. Risk factors for type 1 diabetes include autoimmune, genetic, and environmental factors. Although it usually begins when people are under the age of 30 years, type 1 diabetes may occur at any age. Almost 10% of the United States diabetes population has type 1 diabetes.

Type 2 diabetes was previously called noninsulin-dependent or adult onset diabetes. It begins as insulin resistance, a disorder in which normal-to-excessive amounts of insulin is made by the body, but the cells cannot use insulin properly. The ability to make insulin gradually decreases with time due to the progressive nature of the disease. In its early stages, type 2 diabetes often has no symptoms. When they do occur, symptoms may initiate gradually and include fatigue, dry skin, numbness or tingling in hands or feet, frequent infections, slow healing of cuts and sores, problems with sexual function, and increased hunger and thirst. With type 2 diabetes, hyperosmolar coma can develop from blood glucose levels (often referred to as blood sugar) becoming dangerously high. If the elevated blood sugar is not adequately controlled, it can cause severe dehydration, a serious condition requiring immediate treatment. Type 2 diabetes is associated with obesity, family history of diabetes, prior history of gestational diabetes, impaired glucose tolerance, physical inactivity, and race/ethnicity. Type 2 diabetes is diagnosed in children and adolescents in increasing numbers. About 85% of the U.S. diabetic population has type 2 diabetes.

Gestational diabetes occurs during pregnancy and affects 4% of all pregnant women. During pregnancy, the placenta supplies the baby with glucose and water from the mothers blood. Hormones made by the placenta are needed for pregnancy, but can keep the mothers insulin from functioning efficiently. As the pregnancy continues, more of these hormones are manufactured. When the mother is not able to make enough insulin to compensate for the increased hormone levels and to maintain normal blood glucose, gestational diabetes develops. Treatment is required to normalize maternal blood glucose levels to avoid complications in the fetus. After pregnancy, up to 10% of women with gestational diabetes are found to have type 2 diabetes. Women who have had gestational diabetes have a 20 to 50% chance of developing diabetes in the next five to ten years.

Pre-diabetes

Before type 2 diabetes fulminates (fully develops), people with diabetes usually have a pre-diabetic condition in which blood glucose levels are higher than normal, but not yet high enough for a diagnosis of diabetes. At least 16 million people in the United States between the ages of 40 to 74 years have pre-diabetes. Pre-diabetes is sometimes referred to as insulin resistance, impaired glucose tolerance or impaired fasting glucose. With pre-diabetes, a person is likely to develop diabetes and may already be experiencing the adverse health effects Research has shown that long term damage to the heart and circulatory system may already be occurring during pre-diabetes. Diet, increased activity level, and medication may help to prevent or delay type 2 diabetes from developing. If untreated, most people with pre-diabetes develop type 2 diabetes within three to ten years.

Tests for diabetes

There are three test methods used to diagnose diabetes and each must be confirmed, on a subsequent day, by any one of the three methods. The first method includes symptoms of diabetes (increased urination, increased thirst, unexplained weight loss) plus a casual plasma glucose concentration (blood test taken any time of day without regard to time since last meal) of equal to or greater than 200 mg. The second test method is a fasting plasma glucose (no caloric intake for at least eight hours) of equal to or greater than 126 mg. The third method is a two-hour after meal blood sugar of equal to or greater than 200 mg during an oral glucose tolerance test. Testing for diabetes should be considered in all individuals at age 45 years and above (particularly if overweight), and if normal, should be repeated every three years. Testing should be considered at a younger age or carried out more frequently in individuals who are overweight and who have additional risk factors among the following:

First-degree relative with diabetes,

Habitually physically inactive lifestyle,

Member of high-risk ethnic population (African-American, Hispanic-American, Native American, Asian American, Pacific Islander),

KEY TERMS

Autoimmune response Misdirected immune response in which the bodys immune system accidentally recognizes the bodys own cells as foreign and destroys them. Type 1 diabetes results from an auto-immune response in which the body destroys the beta cells in the pancreas.

Gestational diabetes A type of diabetes that occurs in pregnancy.

Glucose Simple sugar made from other carbohydrates that is circulated in the blood at a narrow limit of concentration. Also known as blood sugar.

Hyperosmolar coma A coma related to high levels of glucose in the blood and requiring emergency treatment. Ketones are not present in the urine; can occur in Type 2 diabetes that is out of control.

Impaired fasting glucose A condition in which fasting glucose levels are greater than 110 mg, but less than 126 mg. Now known as pre-diabetes.

Impaired glucose tolerance A condition in which blood glucose levels rise after meals to levels that are higher than normal. Now called pre-diabetes.

Insulin deficiency A condition in which little or no insulin is produced by the body. Insulin resistanceInability to use the insulin made by the body

Ketoacidosis Formation of ketones (acetones) in the blood from lipid (fat) metabolism and a high blood acid content. Occurs in uncontrolled Type 1 diabetes.

Ketones Acids indicating insufficient insulin that converts fat into glucose in the blood.

Type 1 diabetes A condition in which the body makes little or no insulin (insulin deficiency). People with this type of diabetes must take injections of insulin.

Type 2 diabetes A condition in which the body makes insulin but the cells cannot use it well (insulin resistance). It is treated with diet, exercise, and diabetes medication.

Previous delivery of baby weighing greater than 9 lb (4.1 kg) or history of gestational diabetes,

High blood pressure,

HDL cholesterol less than 35 mg or a triglyceride level greater than 250 mg,

PCOS (polycystic ovarian syndrome),

Impaired glucose tolerance or impaired fasting glucose, and

History of vascular disease.

other tests used in the management of diabetes include c-peptide levels and hemoglobin A1c levels. C-Peptide levels determine if the body is still producing insulin. C-Peptide is the connecting peptide portion of the insulin molecule that is produced in the pancreas. C-Peptide and insulin are secreted into the bloodstream in equal amounts by the pancreas. Measurement of C-Peptide is a reliable indicator of the amount of insulin produced by the persons pancreas. HbA1c (hemoglobin A1c) measures the average blood sugar control over a two to three month period. The A1c goal recommended by the American Diabetes Association is less than 7%, which correlates with average blood sugars of less than 150 mg.

Treatment for diabetes

Diabetes is treated with meal planning, exercise, medication, and blood glucose monitoring. Meal planning involves eating the right amount of food at the right time. Carbohydrates have the greatest impact on blood sugars. Keeping track of carbohydrates and spreading them throughout the day helps to control blood sugars. Exercise helps to reduce stress, control blood pressure and blood fats, and improves insulin resistance.

Diabetes medications include oral agents and insulin. There are several classes of oral medications. Sulfonylureas and meglitinides help the pancreas to produce more insulin. Alpha-glucosidase inhibitors slow down the digestion and absorption of starches and sugars. Biguanides stop the liver from releasing extra sugar when it is not needed. Thiozolidinediones treat insulin resistance.

Various types of insulin are available and have different action times designed to match to physiological needs of the body for persons who no longer make enough insulin. The body requires a continuous, low level of insulin acting to meet baseline needs. Long-acting insulins provide the baseline or basal insulin needs. The body also requires insulin to cover carbohydrates eaten. Short-acting insulins provide coverage for meal boluses. With the wide variety of diabetes medications, the physician can determine a treatment plan that works best for the individual.

Blood glucose monitoring serves as the cornerstone tool for measuring the effects of food, exercise, and diabetes medications. Patients can check their blood sugars at various times of the day to keep track of how well the current treatment plan is keeping the sugars under control. Results of tests are recorded and taken to the physicians office for the doctor to evaluate trends and adjust the treatment plan.

Additional management of diabetes is geared toward prevention of complications. Eye problems may have no symptoms in their early, treatable stages; therefore annual dilated eye examinations are needed. Urine should be checked annually for the protein microalbumin. Poor circulation, nerve damage, and difficulty fighting infections can make foot problems serious considerations for people with diabetes. Daily self-foot examinations and foot exams at each physician visit can help identify problems early. Blood fat (lipidscholesterol and triglyceride) levels should be checked annually.

See also Acids and bases; Metabolic disorders; Metabolism.

Resources

BOOKS

Collazo-Clavell, ed. Mayo Clinic on Managing Diabetes. Rochester, MN: Mayo Clinic, 2006.

Kahn, C. Ronald, ed. Joslins Diabetes Mellitus. Philadelphia, PA: Lippincott Williams & Wilkins, 2005.

PERIODICALS

Davidson, Mayer B, MD. American Diabetes Association: Clinical Practice Recommendations 2003. Diabetes Care (2003): 26 Supp1.

OTHER

American Diabetes Association <http://www.diabetes.org/main/application/commercewf> (accessed November 28, 2006).

Margaret Meyers

Phyllis Tate

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Diabetes Mellitus

Diabetes mellitus is a common metabolic disorder resulting from defects in insulin action, insulin production, or both. Insulin, a hormone secreted by the pancreas, helps the body use and store glucose produced during the digestion of food. Characterized by hyperglycemia , symptoms of diabetes include frequent urination, increased thirst, dehydration , weight loss, blurred vision, fatigue , and, occasionally, coma. Uncontrolled hyperglycemia over time damages the eyes, nerves, blood vessels, kidneys, and heart, causing organ dysfunction and failure. A number of risk factors are attributed to the incidence of diabetes, including family history, age, ethnicity, and social group characteristics, as well as behavioral , lifestyle, psychological , and clinical factors.

The World Health Organization estimates that 150 million people had diabetes worldwide in 2002. This number is projected to double by the year 2025. Much of this increase will occur in developing countries and will be due to population growth, aging, unhealthful diets, obesity , and sedentary lifestyles. In the United States, diabetes is the sixth leading cause of death. While 6.2 percent of the population has diabetes, an estimated 5.9 million people are unaware they have the disease. In addition, about 19 percent of all deaths in the United States for those age twenty-five and older are due to diabetes-related complications.

The prevalence of diabetes varies by age, gender, race, and ethnicity. In the United States, about 0.19 percent of the population less than twenty years of age (151,000 people) have diabetes, versus 8.6 percent of the population twenty years of age and older. In addition, adults sixty-five and older account for 40 percent of those with diabetes, despite composing only 12 percent of the population. Considerable variations also exist in the prevalence of diabetes among various racial and ethnic groups. For example, 7.8 percent of non-Hispanic whites, 13 percent of non-Hispanic blacks, 10.2 percent of Hispanic/Latino Americans, and 15.1 percent of American Indians and Alaskan Natives have diabetes. Among Asian Americans and Pacific Islanders, the rate of diabetes varies substantially and is estimated at 15 to 20 percent. The prevalence of diabetes is comparable for males and females8.3 and 8.9 percent respectively. Nevertheless, the disease is more devastating and more difficult to control among women, especially African-American and non-Hispanic white women. In fact, the risk for death is greater among young people (3.6 times greater for people from 25 to 44 years of age) and women (2.7 times greater for women ages 45 to 64 than men of the same age).

Types of Diabetes

Diabetes mellitus is classified into four categories: type 1, type 2, gestational diabetes, and other. In type 1 diabetes, specialized cells in the pancreas are destroyed, leading to a deficiency in insulin production. Type 1 diabetes frequently develops over the course of a few days or weeks. Over 95 percent of people with type 1 diabetes are diagnosed before the age of twenty-five. Estimates show 5.3 million people worldwide live with type 1 diabetes. Although the diagnosis of type 1 diabetes occurs equally among men and women, an increased prevalence exists in the white population. Type 1 diabetes in Asian children is relatively rare.

Family history, diet , and environmental factors are risk factors for type 1 diabetes. Studies have found an increased risk in children whose parents have type 1 diabetes, and this risk increases with maternal age. Environmental factors such as viral infections, toxins , and exposure to cow's milk are being contested as causing or modifying the development of type 1 diabetes.

Type 2 diabetes is characterized by insulin resistance and/or decreased insulin secretion. It is the most common form of diabetes mellitus, accounting for 90 to 95 percent of all diabetes cases worldwide. Risk factors for type 2 diabetes include family history, increasing age, obesity, physical inactivity, ethnicity, and a history of gestational diabetes. Although type 2 diabetes is frequently diagnosed in adult populations, an increasing number of children and adolescents are currently being diagnosed. Type 2 diabetes is also more common in blacks, Hispanics, Native Americans, and women, especially women with a history of gestational diabetes.

Genetics and environmental factors are the main contributors to type 2 diabetes. Physical inactivity and adoption of a Western lifestyle (particularly choosing foods with more animal protein , animal fats, and processed carbohydrates ), especially in indigenous people in North American and within ethnic groups and migrants, have contributed to weight gain and obesity. In fact, obesity levels increased by 74 percent between 1991 and 2003. Increased body fat and abdominal obesity are associated with insulin resistance, a precursor to diabetes. Impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) are two prediabetic conditions associated with insulin resistance. In these conditions, the blood glucose concentration is above the normal range, but below levels required to diagnose diabetes. Subjects with IGT and/or IFG are at substantially higher risk of developing diabetes and cardiovascular disease than those with normal glucose tolerance. The conversion of individuals with IGT to type 2 diabetes varies with ethnicity, anthropometric measures related to obesity, fasting blood glucose (a measurement of blood glucose values after not eating for 12 to 14 hours), and the two-hour post-glucose load level (a measurement of blood glucose taken exactly two hours after eating). In addition to IGT and IFG, higher than normal levels of fasting insulin, called hyperinsulinemia, are associated with an increased risk of developing type 2 diabetes. Insulin levels are higher in African Americans than in whites, particularly African-American women, indicating their greater predisposition for developing type 2 diabetes.

The complexity of inheritance and interaction with the environment makes identification of genes involved with type 2 diabetes difficult. Only a small percentage (25%) of diabetes cases can be explained by single gene defects and are usually atypical cases. However, a "thrifty gene," although not yet identified, is considered predictive of weight gain and the development of type 2 diabetes. Thrifty-gene theory suggests that indigenous people who experienced alternating periods of feast and famine gradually developed a way to store fat more efficiently during periods of plenty to better survive famines. Regardless of the thrifty gene, the contribution of genetic mutations in the development of type 2 diabetes has not been established, due to the number of genes that may be involved.

Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance with onset or first recognition during pregnancy. This definition applies regardless of whether insulin or diet modification is used for treatment, and whether or not the condition persists after pregnancy. GDM affects up to 14 percent of the pregnant populationapproximately 135,000 women per year in United States. GDM complicates about 4 percent of all pregnancies in the U.S. Women at greatest risk for developing GDM are obese , older than twenty-five years of age, have a previous history of abnormal glucose control, have first-degree relatives with diabetes, or are members of ethnic groups with a high prevalence of diabetes. Infants of a woman with GDM are at a higher risk of developing obesity, impaired glucose tolerance, or diabetes at an early age. After a pregnancy with GDM, the mother has an increased risk of developing type 2 diabetes.

Other forms of diabetes are associated with genetic defects in the specialized cells of the pancreas, drug or chemical use, infections, or other diseases. The most notable of the genetically linked diabetes is maturity onset diabetes of the young (MODY). Characterized by the onset of hyperglycemia before the age of twenty-five, insulin secretion is impaired while minimal or no defects exist in insulin action. Drugs , infections, and diseases cause diabetes by damaging the pancreas and/or impairing insulin action or secretion.

Diabetes Complications

People with diabetes are at increased risk for serious long-term complications. Hyperglycemia, as measured by fasting plasma glucose concentration or glycosylated hemoglobin (HbA1c), causes structural and functional changes in the retina, nerves, kidneys, and blood vessels. This damage can lead to blindness, numbness, reduced circulation, amputations, kidney disease, and cardiovascular disease. Type 1 diabetes is more likely to lead to kidney failure. About 40 percent of people with type 1 diabetes develop severe kidney disease and kidney failure by the age of fifty. Nevertheless, between 1993 and 1997, more than 100,000 people in the United States were treated for kidney failure caused by type 2 diabetes.

African Americans experience higher rates of diabetes-related complications such as eye disease, kidney failure, and amputations. They also experience greater disability from these complications. The frequency of diabetic retinopathy (disease of the small blood vessels in the retina causing deterioration of eyesight) is 40 to 50 percent higher in African Americans than in white Americans. In addition, the rate of diabetic retinopathy among Mexican Americans is more than twice that of non-Hispanic white Americans. Furthermore, African Americans with diabetes are much more likely to undergo a lower-extremity amputation than white or Hispanic Americans with diabetes. Little is known about these complications in Asian and Pacific Islander-Americans.

Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemia state (HHS) are serious diabetic emergencies and the most frequent cause of mortality. Both DKA and HHS result from an insulin deficiency and an increase in counter-regulatory hormones (a.k.a. hyperglycemia). Hyperglycemia leads to glycosuria (glucose in the urine), increased urine output, and dehydration. Because the glucose is excreted in the urine, the body becomes starved for energy . At this point, the body either continues to excrete glucose in the urine making the hyperglycemia worse (HHS), or the body begins to break down triglycerides causing the release of ketones (by-products of fat breakdown) into the urine and bloodstream (DKA). The mortality rate of patients with DKA is less than 5 percent while the mortality rate of HHS patients is about 15 percent. Infection (urinary tract infections and pneumonia account for 30 to 50 percent of cases), omission of insulin, and increased amounts of counter-regulatory hormones contribute to DKA and HHS. Type 1 and type 2 diabetic patients may experience DKA and HHS. However, DKA is more common in type 1 diabetic patients, while HHS is more common in type 2 diabetic patients. Treatment of DKA and HHS involves correction of dehydration, hyperglycemia, ketoacidosis, and electrolyte deficits and imbalances.

Treatment for Diabetes

Treatment for diabetes involves following a regimen of diet, exercise, self-monitoring of blood glucose, and taking medication or insulin injections. Although type 1 diabetes is primarily managed with daily insulin injections, type 2 diabetes can be controlled with diet and exercise. However, when diet and exercise fail, medication is added to stimulate the production of insulin, reduce insulin resistance, decrease the liver's output of glucose, or slow absorption of carbohydrate from the gastrointestinal tract. When medication fails, insulin is required.

Following the diagnosis of diabetes, a diabetic patient undergoes medical nutrition therapy. In other words, a registered dietician performs a nutritional assessment to evaluate the diabetic patient's food intake, metabolic status, lifestyle, and readiness to make changes, along with providing dietary instruction and goal setting. The assessment is individualized and takes into account cultural, lifestyle, and financial considerations. The goals of medical nutrition therapy are to attain appropriate blood glucose, lipid, cholesterol , and triglyceride levels, which are critical to preventing the chronic complications associated with diabetes. For meal planning, the diabetic exchange system provides a quick method for estimating and maintaining the proper balance of carbohydrates, fats, proteins, and calories . In the exchange system, foods are categorized into groups, with each group having food with similar amounts of carbohydrate, protein, fat, and calories. Based on the individual's diabetes treatment plan and goals, any food on the list can be exchanged with another food within the same group.

Exercise and blood glucose monitoring are also critical components of a diabetic patient's self-management. Exercise improves blood glucose control, increases sensitivity to insulin, reduces cardiovascular risk factors, contributes to weight loss, and improves well-being. Exercise further contributes to a reduction in the risk factors for diabetes-related complications. Daily self-monitoring of blood glucose levels allows diabetic patients to evaluate and make adjustments in diet, exercise, and medications. Self-monitoring also assists in preventing hypoglycemic episodes.

Diabetes, Heart Disease, and Stroke

Many people with diabetes are not aware that they are at particularly high risk for heart disease and stroke, which can result from the poor blood flow that is a symptom of diabetes. In addition, people with type 2 diabetes have higher rates of hypertension and obesity, which are additional risk factors. Diabetics are two to four times more likely to have a heart attack than nondiabetics, and at least 65 percent of people with diabetes die from heart attack or stroke. While deaths from heart disease have been declining overall, deaths from heart disease among women with diabetes have increased, and deaths from heart disease among men with diabetes have not declined nearly as rapidly as they have among the general male population. The National Diabetes Education Program has launched a campaign to bring the problem to public attention. Patients are advised to work with medical personnel to control their glucose level, blood pressure, and cholesterol level and, of course, to avoid smoking.

Diabetes mellitus is a chronic and debilitating disease. Attributed to genetics, physical inactivity, obesity, ethnicity, and a number of environmental factors, diabetes requires lifestyle changes and medication adherence in order to control blood glucose levels. Due to the damage caused by hyperglycemia, diabetic patients also experience a number of complications related to the disease. With good self-management practices, however, individuals with diabetes can live a long and productive life.

see also Carbohydrates; Exchange System; Glycemic Index; Hyperglycemia; Hypoglycemia; Insulin.

Julie Lager

Bibliography

American Diabetes Association (2003) "Gestational Diabetes Mellitus." Diabetes Care 26(1):S103S105.

American Diabetes Association (2003) "Hyperglycemic Crises in Patients with Diabetes Mellitus." Diabetes Care 26(1):S109S117.

American Diabetes Association (2003) "Physical Activity/Exercise and Diabetes Mellitus." Diabetes Care 26(1):S7377.

American Diabetes Association (2003) "Standards of Medical Care for Patients with Diabetes Mellitus." Diabetes Care 26(1):S33S50.

Atkinson, Mark A., and Eisenbarth, George S. (2001). "Type 1 Diabetes: New Perspectives on Disease Pathogenesis and Treatment." Lancet 358:221229.

Black, Sandra A. (2002). "Diabetes, Diversity, and Disparity: What Do We Do with the Evidence?" American Journal of Public Health 92(4):543548.

Chiasson, Jean-Louis; Aris-Jilwan, Nahla; Belanger, Raphael; Bertrand, Sylvie; Beauregard, Hugues; Ekoe, Jean-Marie; Fournier, Helene; and Havrankova, Jana (2003). "Diagnosis and Treatment of Diabetic Ketoacidosis and the Hyperglycemic Hyperosmolar State." Canadian Medical Association Journal 168(7):859866.

Green, Anders (1996). "Prevention of IDDM: The Genetic Epidemiologic Perspective." Diabetes Research and Clinical Practice 34:S101S1006.

Mandrup-Paulson, Thomas (1998). "Recent Advances: Diabetes." British Medical Journal 316(18):12211225.

Mokdad, Ali H.; Ford, Earl S.; Bowman, Barbara A.; Dietz, William, H.; Vinicor, Frank; Bales, Virginia, S.; and Marks, James S. (2003). "Prevalence of Obesity, Diabetes, and Obesity-Related Health Risk Factors, 2001." Journal of the American Medical Association 289(1):7679.

Jovanovic, Lois, and Pettitt, David J. (2001). "Gestational Diabetes Mellitus." Journal of the American Medical Association 283(20):25162518.

Kitabchi, Abbas E.; Umpierrez, Guillermo E.; Murphy, Mary Beth; Barrett, Eugene J.; Kreisberg, Robert A.; Malone, John I.; and Wall, Barry M. (2001). "Management of Hyperglycemic Crises in Patients with Diabetes." Diabetes Care 24(1):131153.

Simpson, R. W.; Shaw, J. E.; and Zimmet, P. Z. (2003). "The Prevention of Type 2 DiabetesLifestyle Change or Pharmacotherapy? A Challenge for the 21st Century." Diabetes Research and Clinical Practice 59:165180.

Yki-Jarvinen, Hannele (1998). "Toxicity of Hyperglycemia in Type 2 Diabetes." Diabetes/Metabolism Reviews 14:S45S50.

Internet Resources

American Diabetes Association. "Basic Diabetes Information." Available from <http://www.diabetes.org>

Centers for Disease Control and Prevention. "Diabetes Public Health Resource." Available from <http://www.cdc.gov/diabetes>

National Diabetes Information Clearinghouse (NDIC). "Diabetes." Available from <http://diabetes.niddk.nih.gov>

World Health Organization. "Fact Sheets: Diabetes Mellitus." Available from <http://www.who.int>

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