glucose tolerance test

glucose tolerance test (oral glucose tolerance test) n. the standard diagnostic test for diabetes mellitus and the related condition, impaired glucose tolerance (IGT). Blood-sugar levels are measured after an overnight fast and again after oral administration of 75 g glucose. Diabetes is diagnosed if the fasting level is above 7.0 mmol/l and/or the two-hour level is above 11.1 mmol/l. IGT is diagnosed when the fasting level is below 7.0 mmol/l and the two-hour level is between 7.0 mmol/l and 11.1 mmol/l.