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Optimal Range of HbA1c for the Prediction of Future Diabetes

Sep 8, 2011

An HbA1c cut-point of 5.7% is a suitable value for predicting future diabetes. It is reasonable to consider an HbA1c range of 5.7-6.4% as a category of increased risk for diabetes, similar to an IFG or IGT.

In a 4-year longitudinal study, a retrospective analysis was conducted among subjects who participated in comprehensive health check-ups annually for 5 years. Then, a total of 9723 subjects were classified into 12 categories based on the baseline HbA1c level.   


The results showed that during 4 years, 601 of the 9723 subjects (6.2%) developed diabetes.  Based on ROC analysis, an HbA1c of 5.7% gave an optimal sensitivity of 62% and specificity of 85% to predict diabetes.

The point showing a substantial difference in the Kaplan-Meier curves was an HbA1c of 5.7%. The incidence of diabetes was 20.8% among subjects with a baseline HbA1c of 5.7-6.4%. The hazard ratio of developing diabetes was 6.5 (95% CI, 3.7–10.2) in the subjects with an HbA1c of 5.7% compared with the bottom category of HbA1c (<5.0%).

Diabetes Research and Clinical Practice, 08/16/2011

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