Using Glycosylated Hemoglobin to Define the Metabolic Syndrome in United States Adults

OBJECTIVE: To compare the use of GHb and fasting plasma glucose (FPG) to define the metabolic syndrome (MetS). RESEARCH DESIGN AND METHODS: Data from the U.S. National Health and Nutrition Examination Survey 1999–2006 were used. MetS was defined using the consensus criteria in 2009. Raised blood glucose was defined as either FPG ≥100 mg/dl (5.6 mmol/l) or GHb ≥5.7%. RESULTS: In 2003–2006, there was 91.3% agreement between GHb and FPG when either was used to define MetS. The agreement was good irrespective of age, sex, race/ethnicity, BMI, and diabetes status (≥87.4%). Similar results were found in 1999–2002. Among subjects without diabetes, only the use of GHb alone, but not FPG, resulted in significant association with cardiovascular diseases (odds ratio 1.45, P = 0.005). CONCLUSIONS: Using GHb instead of FPG to define MetS is feasible. It also identifies individuals with increased cardiovascular risk.