1. Normal blood glucose level The normal 8-hour fasting plasma glucose (FPG) level is <100 mg/dL, and the normal 2-hour plasma glucose during 75 g oral glucose tolerance test (OGTT) is <140 mg/dL.

2. Diagnostic criteria for diabetes

1) Glycosylated hemoglobin (HbA1c; HbA1c should be measured using the standardized method) ≥6.5%, or

2) 8-hour FPG level ≥126 mg/dL, or

3) 2-hour plasma glucose during 75 g OGTT ≥200 mg/dL, or

4) Presence of typical symptoms of diabetes (polyuria, polydipsia, and unexplained weight loss) with random plasma glucose level ≥200 mg/dL

-If an individual meets any of 1)–3) of the diagnostic criteria, tests should be repeated on different days. However, an immediate diagnosis can be made if the individual meets at least two criteria from the tests simultaneously performed.

3. Diagnostic criteria for prediabetes

1) Impaired fasting glucose (IFG): FPG level 100–125 mg/dL, or

2) Impaired glucose tolerance (IGT): 2-hour plasma glucose during 75 g OGTT 140–199 mg/dL, or

3) HbA1c: 5.7%–6.4%