Use of HbA1c in predicting progression to diabetes in French men and women -: Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR)

OBJECTIVE - Early identification of subjects at high risk for diabetes is essential, and random HbA(1c) (AlC) may be more practical than fasting plasma glucose (FPG). The predictive value of AlC, in comparison to FPG, is evaluated for 6-year incident diabetes. RESEARCH DESIGN AND METHODS - From the French cohort study Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR), 1,383 men and 1,437 women, aged 30-65 years, were volunteers for a routine health check-up. Incident diabetes was defined by FPG 7.0 mmol/l or treatment by antidiabetic drugs. Multivariate logistic regression models were used to predict diabetes at 6 years. Receiver operating characteristic curves compared the predictive values of AlC and FPG. RESULTS - At 6 years, 30 women (2.1%) and 60 men (4.3%) had developed diabetes. Diabetes risk increased exponentially with AlC in both sexes (P < 0.001). After stratifying on FPG, AlC predicted diabetes only in subjects with impaired fasting glucose (IFG) (FPG >= 6.10 mmol/l): the odds ratio (95% CI) for a 1% increase in AlC was 7.20 (3.00-17.00). In these subjects, an AlC of 5.9% gave an optimal sensitivity of 64% and specificity of 77% to predict diabetes. CONCLUSIONS - AlC predicted diabetes, even though the diagnosis of diabetes was based on FPG but it was less sensitive and specific than FPG. It could be used as a test if fasting blood sampling was not available or in association with FPG. In subjects with IFG, AlC is better than glucose to evaluate diabetes risk, and it could be used to select subjects for intensive early intervention.