Glycated haemoglobin as a predictor for metabolic syndrome in non-diabetic Korean adults

AIMS With increasing prevalence of diabetes mellitus and metabolic syndrome (MS), the importance of early detection of insulin resistance is emphasized. However, a simple and practical method of measurement is not readily available. Therefore, we examined the sensitivity and specificity of HbA(1c) for predicting impaired fasting glucose (IFG) and MS and its association with cardiovascular risk factors, particularly in the normal range of HbA(1c) levels in non-diabetic Korean subjects. METHODS In 40,155 participants (median age 40 years) participating in a medical check-up programme, analysis of the distribution of HbA(1c) and its association with various cardiovascular risk factors was performed. In 22,465 selected participants, an analysis was conducted of the ability of HbA(1c) to predict MS and IFG. Anthropometric measurements were made in all subjects and fasting glucose, lipid profiles and HbA(1c) were measured. The presence of MS was defined according to the definitions of the Adult Treatment Panel III (ATP III) guideline and the new International Diabetes Federation (IDF) guideline. Patients with diabetes were excluded from the study. RESULTS The incidence of MS was 12.2% according to ATP III criteria and 7.6% according to IDF criteria. When subjects were grouped by quartile of HbA(1c), cardiovascular risk factors significantly increased as the HbA(1c) increased. An HbA(1c) of 5.45% predicted the presence of MS (ATP III: sensitivity/specificity 57.4/64.3%, area under the curve 64.8%; IDF: sensitivity 60.2/63.4%, area under the curve 66.1%) and fasting blood glucose > or = 5.6 mmol/l (sensitivity/specificity 53.7/70%, area under the curve 66.1%). When the analyses were done separately by gender, female subjects showed higher cut-off of HbA(1c) for the prediction of MS (5.55% for both ATP III and IDF criteria). CONCLUSIONS HbA(1c) increased as cardiovascular risk factors increased and HbA(1c) of 5.45% predicted the presence of MS. HbA(1c) might be a predictive measure of IFG and MS, and also cardiovascular risk factors in the Korean population.