Follow-up Report on the Diagnosis of Diabetes Mellitus

Reprinted with permission from Diabetes Care 26:3160–3167, 2003

In 1997, an International Expert Committee was convened to reexamine the classification and diagnostic criteria of diabetes, which were based on the 1979 publication of the National Diabetes Data Group1 and subsequent WHO study group.2 As a result of its deliberations, the Committee recommended several changes to the diagnostic criteria for diabetes and for lesser degrees of impaired glucose regulation (IFG/IGT).3 The following were the major changes or issues addressed.

1) The use of a fasting plasma glucose (FPG) test for the diagnosis of diabetes was recommended, and the cut point separating diabetes from nondiabetes was lowered from FPG ≥ 140 mg/dl (7.8 mmol/l) to ≥ 126 mg/dl (7.0 mmol/l). (All glycemic values represent venous plasma.) This change was based on data that showed an increase in prevalence and incidence of diabetic retinopathy beginning at approximately an FPG of 126 mg/dl, as well as on the desire to reduce the discrepancy that existed in the number of cases detected by the FPG cut point of ≥ 140 mg/dl and the 2-h value in the OGTT (2-h plasma glucose [2-h PG]) of ≥ 200 mg/dl (11.1 mmol/l).

2) Normal FPG was defined as < 110 mg/dl (6.1 mmol/l).

3) The use of HbA_1c (A1C) as a diagnostic test for diabetes was not recommended. The primary reason for this decision was a lack of standardized methodology resulting in varying nondiabetic reference ranges among laboratories.

4) Although the OGTT (which consists of an FPG and 2-h PG value) was recognized as a valid way to diagnose diabetes, the use of the test for diagnostic purposes in clinical practice was discouraged for several reasons (e.g., inconvenience, less reproducibility, greater cost). The diagnostic category of impaired glucose tolerance (IGT) was retained to describe …