Clinical Research of Glycated Hemoglobin for Diagnosis of Diabetes Mellitus and Pre-Diabetes

Objective:To assess the diagnostic value of glycated hemoglobin (HbA1c) for diabetes mellitus (DM) and pre-diabetes. Methods: Four hundred and fifty-seven subjects (297 male, 160 female,average age 61.4 years±13.1 years), for screening diabetes, underwent an oral glucose tolerance test (OGTT). The value of HbA1c was examined as well. Based on 1999 WHO criteria,subjects were divided into normal glucose tolerance group (NGT, n=81), impaired fasting glucose group (IFG, n=7), impaired glucose tolerance group (IGT, n=76), IFG+IGT group (n=13) and DM group (n=280). The receiver operat ing characteristic curve (ROC curve) was used to judge the optimal cut-point. Results: The optimal cut-point of HbA1c for DM was 6.45% that was associated with the sensitivity and specificity of 0.794 and 0.825 respectively. The area under the curve was 0.871 (95% CI 0.839-0.903). The cut-point of HbAlc for pre-diabetes was 5.85%,which was associated with the sensitivity and specificity of 0.583 and 0.531 respectively. The area under the curve was 0.587(95% CI 0.504-0.671). When HbA1c≥6.45% was used to diagnose diabetes, the misdiagnosis rate was 21.1%. When FPG≥7.0 mmol/L or HbA1c≥ 6.45% was used to diagnose diabetes, the sensitivity was 0.871, specificity was 0.623 and the rate of misdiagnosis was 12.9%. Conclusion: The detection of FPG and HbA1c may reduce the misdiagnosis rate of T2DM.