How Do We Diagnose Diabetes and Measure Blood Glucose Control?

Abstract

In BriefIn 1979, criteria for the diagnosis of diabetes were selected based on levels of glycemia on the oral glucose tolerance test (OGTT) that were associated with the subsequent development of retinopapthy. Since then, five long-term studies have demonstrated that when HbA1c levels are maintained below 7% (normal 6%), development of retinopathy and microalbuminuria is practically nil. Approximately 60% of people with fasting plasma glucose (FPG) concentrations of 126–139 mg/dl and 70% of those with 2-h values on the OGTT of 200–239 mg/dl have normal HbA1c levels, with another third having values between 6 and 7%. This article offers an alternative approach to diagnosis using both FPG and HbA1c values.