In 1997, the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus published a new classification scheme and revised diagnostic criteria for diabetes mellitus (the following criteria are from the 2013 revision).
Diagnostic elements: genetic markers; autoantibodies, clinical characteristics (ketosis, pattern of progression, obesity, age and treatment response)
Type 1: β-cell destruction usually leading to absolute insulin deficiency
Type 2: Insulin resistance with insulin secretion deficiency. 90 - 95% of people who have diabetes have Type 2.
Other specific types:
Genetic defects in β-cell function
Genetic defects in insulin action
Exocrine pancreas diseases
Drug- or chemical-induced
Other rare forms
(Any finding falling within a positive criteria should be repeated on a subsequent day with another test in any criteria set: e.g., a random plasma glucose with symptoms, might be followed-up with a fasting plasma glucose.)
Fasting plasma glucose (FPG) ≥ 126 mg/dl (7.0 mmol/l) OR
Symptoms (such as polyuria, polydipsia, unexplained weight loss) AND
a random plasma glucose ≥ 200 mg/dl (11.1 mmol/l) OR
Plasma glucose ≥ 200 mg/dl ( 11.1 mmol/l) 2 hours after a 75g glucose load OR
A1C ≥ 6.5%.
Categories of increased risk for diabetes (prediabetes):
Fasting plasma glucose (FPG) levels: 100 to 125mg/dl (5.6 - 6.9mmol/l) [IFG]; OR
2-h PG values in the 75-g oral glucose tolerance test (OGIT)): 140 mg/dl to 199 mg/dl (7.8 - 11.0 mmol/l) [IGT]; OR
A1C: 5.7 - 6.4%.
Screen at 24-28 weeks
75g OGTT: fasting: ≥ 92mg/dl (5.1 mmol/l) ; OR
1 hr: ≥ 180mg/dl (10.0 mmol/l); OR
2 hr: ≥ 153mg/dl (8.5 mmol/l).