Utility of hemoglobin A1c for diagnosing metabolic syndrome in Chinese subjects over 50 years old

Abstract

Objective: To evaluate glycated hemoglobing A1c (HbA1c) in diagnosing metabolic syndrome (MS) in Chinese subjects aged over 50 years. Methods: A community-based cross-sectional survey was conducted between October 2010 and January 2011 in Shipai community, Guangzhou. A total of 1 494 subjects aged over 50 years were investigated. Questionnaire survey and physical examination were performed among all participants. Fasting blood samples were obtained to measure plasma glucose (FPG), blood lipids and HbA1c. MS was defined by the criteria of International Diabetes Federation (IDF), National Cholesterol Education Program-Adult Treatment Panel Ⅲ (ATP Ⅲ)(2005) and Chinese Diabetes Society (CDS), respectively. Receiver operating characteristic (ROC) curves were plotted to explore the accuracy of HbA1c for diagnosing MS. Results: After excluding subjects with missing data, the remaining 1 473 subjects had a median age of 61 years (55-68 years). An HbA1c threshold of 6.1% yielded the highest combination of sensitivity (52.1%) and specificity (84.3%) for diagnosing MS. Using HbA1c≥5.7% as definition of dysglycemia, the prevalence of MS (IDF), MS (ATP Ⅲ) and MS (CDS) were 48.7%, 57.1% and 50.8%, respectively. The κ coefficients were 0.853, 0.768 and 0.730, respectively. Using HbA1c≥6.1% as definition of dysglycemia, the prevalences of MS (IDF), MS (ATP Ⅲ) and MS (CDS) were 41.2%, 45.8% and 39.1%, respectively. The κ coefficients were 0.923, 0.880 and 0.881, respectively. The optimal HbA1c threshold with the highest level of agreement according to IDF, ATP Ⅲ and CDS criteria were 6.1%, 6.3% and 6.3%, respectively. Conclusions: An HbA1c threshold of 6.1% showed a high specificity for diagnosing MS in Chinese subjects aged over 50 years in community-based setting. The optimal HbA1c threshold may vary according to different criteria and populations.