Optimal range of HbA1c for the prediction of future diabetes: A 4-year longitudinal study

Diabetes Research and Clinical Practice, 08/16/2011

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


  • A retrospective analysis was conducted among subjects who participated in comprehensive health check–ups annually for 5 years.
  • A total of 9723 subjects were classified into 12 categories based on the baseline HbA1c level.


  • During 4 years, 601 of the 9723 subjects (6.2%) developed diabetes.
  • Based on ROC analysis, a 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 a 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 a HbA1c of 5.7% compared with the bottom category of HbA1c (<5.0%).

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