Table 13

 Diagnosis of diabetes mellitus, impaired fasting glucose (IFG), and impaired glucose tolerance (IGT)

Fasting plasma glucose (FPG) test (preferred)*Random plasma glucose testOral glucose tolerance test (OGTT)
*The FPG is the preferred test for diagnosis, but any one of the three listed is acceptable. In the absence of unequivocal hyperglycaemia with acute metabolic decompensation, one of these three tests should be repeated on a different day to confirm diagnosis. Venous plasma samples are used (symptoms are the classic ones of polyuria, polydipsia, and unexplained weight loss).
†Fasting is defined as no caloric intake for at least 8 hours. Water is allowed.
‡Random  =  any time of day without regard for time since last meal.
§OGTT should be performed using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water.
Diabetes FPG⩾ 7.0 mmol/l plus symptoms†Random plasma glucose ⩾11.1 mmol/l plus symptoms‡2-hour plasma glucose ⩾ 11.1 mmol/l§
Impaired glucose regulation IFG ⩾6.1 and <7.0 mmol/lIGT  =  2 h PG ⩾7.8 and <11.1 mmol/l
Normal FPG ⩽ 6.0 mmol/l2 h PG <7.8 mmol/l