Objective: The 1997 American Diabetes Association (ADA) and the 1985 and 1999 World Health Organization (WHO) criteria for diabetes and hyperglycemia differ. The appropriateness of these diagnostic criteria in terms of individuals identified as abnormal and their prognosis has been debated. The purpose of this study is to compare the classifications of people by these criteria and to compare fasting and postload plasma glucose concentrations in the prediction of diabetes.
Research design and methods: The frequencies of diabetes by the 3 sets of criteria were compared in 5,023 adult Pima Indians not taking hypoglycemic drugs. Among nondiabetic subjects, fasting plasma glucose (FPG) and 2-h postload plasma glucose (2-h PG) concentrations and categories of impaired glucose regulation or diabetes were evaluated as predictors of diabetes defined by 1999 WHO criteria.
Results: The frequency of diabetes was 12.5% by 1997 ADA criteria, 14.6% by 1985 WHO criteria, and 15.3% by 1999 WHO criteria. The incidence of diabetes was strongly related to higher FPG and 2-h PG, each of which had very similar predictive powers. Impaired glucose tolerance (IGT) was more common than impaired fasting glucose (IFG) (15 vs. 5%), but the 5-year incidence of diabetes was higher in IFG than IGT (37 vs. 24%).
Conclusions: The prevalence and incidence of diabetes are somewhat lower with the ADA criteria than with the 1985 or 1999 WHO criteria. The intermediate categories of glycemia differ substantially IFG defines a smaller number of people who are at higher risk of developing diabetes than those with IGT. More people at high risk of diabetes could be identified by using either IFG or IGT, as recommended by the 1999 WHO criteria, or by using the FPG concentration alone, but with a lower cutoff value.