Aims: To examine whether hemoglobin A1c (HbA1c) can be used instead of fasting plasma glucose (FPG) to identify nondiabetic Chinese adolescents with metabolic syndrome (MS).
Methods: This was a cross-sectional study involving 910 adolescents (11–16 years; 46.8% girls) with an HbA1c less than or equal to 6.4% and an FPG less than or equal to 6.9 mmol/L. All participants underwent anthropometric and biochemical examinations. Metabolic syndrome was defined using the definition proposed by the International Diabetes Federation (IDF) and the American Heart Association (AHA). Replacement of an FPG greater than or equal to 5.6 mmol/L with an HbA1c greater than or equal to 5.7% yielded 2 HbA1c definitions (IDF-HbA1c and AHA-HbA1c). The use of an HbA1c greater than or equal to 5.7% or an FPG greater than or equal to 5.6 mmol/L in the definition of the glycemic component of the MS was compared.
Results: The HbA1c definition resulted in an increase in the population prevalence of MS by 2.4% (IDF-HbA1c) and 2.5% (AHA-HbA1c), respectively (P ≥ 0.05). The degree of concordance (κ index) was as high as 0.900 for the concordance between the IDF and IDF-HbA1c definition, and 0.811 between the AHA and AHA-HbA1c definition. Subjects who were diagnosed as normal based on the FPG definition and met the HbA1c definition for MS had more cardiometabolic risk factors (waist circumference, blood pressure, lipid profiles, uric acid, and homeostasis assessment model of insulin resistance; all P < 0.05), indicating that the HbA1c definition identified more subjects with cardiovascular disease–related risk factors. HbA1c greater than or equal to 5.7% was significantly associated with the presence of MS [adjusted odds ratio, 2.61 (1.13–6.01)].
Conclusions: An HbA1c greater than or equal to 5.7% was associated with the presence of MS and can be considered a surrogate for FPG in the diagnosis of MS in nondiabetic Chinese adolescents.