Introduction: In2010, the American Diabetes Association(ADA) recommended HbA1c value of 5.7-6.4% was defined as pre-diabetes and HbA1c value of 6.5% was selected as the diagnostic cut off for diabetes.Current researches for identifying pre-diabetes and diabetes has been largely studied in adult populations, we have to think whether the criteria used for adults best serve us to make the diagnosis of diabetes or pre-diabetes in adolescents and the youths, especially in Chinese population.

　　 　　 OBJECTIVE: The aim of this study was to assess HbA1c for the diagnosis of pre-diabetes and diabetes in a population of Chinese adolescents and young adults at a high risk of diabetes.

　　 　　 RESEARCH DESIGN AND METHODS: The study cohort consisted of 559 individuals, recruited from the cohort of Beijing Child and Adolescent Metabolic Syndrome (BCAMS) study, without a diagnosis of diabetes at baseline, with a follow-up time of 10 years. All subjects underwent an oral glucose tolerance test (OGTT) and HbA1c measurement. ROC curve analysis was performed for evaluating HbA1c screening efficacy.

　　 　　 Results: Subjects were stratified according to HBA1c categories: 85.5% with normal glucose tolerance (HBA1c<5.7%), 13.3% at risk for diabetes (HBA1c 5.7-6.4%), and 1.2% with diabetes (HBA1c>6.5%). In the at risk for diabetes category, 28.9% were classified with prediabetes or diabetes, and in the diabetes category, 80 % were classified with type 2 diabetes by the OGTT. In the type 2 diabetes category, the AUC for HbA1c to diagnosed was 0.968. The optimal threshold of HbA1c was 6.1% in identifying type 2 diabetes, with a specificity of 99.1% and sensitivity of 88.9%. For pre-diabetes, the AUC for HBA1c was 0.683.The optimal threshold was 5.5%, with a specificity of 67.4% and sensitivity of 61.9%.

　　 　　 The ADA suggested that an HbA1c of 5.7% and 6.5% may not serve us to make the diagnosis of diabetes or pre-diabetes in adolescents and the youths, especially in Chinese population.