Diagnostic Criteria for Metabolic Syndrome: Caucasians Versus African-Americans

Background: Metabolic syndrome is a constellation of risk factors used to identify individuals at greatest risk for developing cardiovascular disease (CVD). Early diagnosis of CVD would benefit African-Americans (AA), who have a higher prevalence of and mortality rate from CVD compared to Caucasians (CA). Two definitions for metabolic syndrome were used to classify healthy CA and AA, and evaluate how other CVD risk factors [C-reactive protein (CRP), percent body fat, fitness level, insulin resistance, and non-high-density lipoprotein cholesterol (HDL-C)] changed metabolic syndrome classification. Methods: Healthy AA (n = 97) and CA (n = 51) ranging from normal weight to obese, 18-45 years of age, with neither hypertension nor diabetes, were evaluated for cardiorespiratory fitness, height, weight, percent body fat, hip and waist circumference, blood pressure (BP), and fasting blood glucose, insulin, triglycerides, HDL, non-HDL-C, and CRP. Participants were classified as meeting the criteria for metabolic syndrome according to the National Cholesterol Education Program Adult Treatment Panel III 2004 (NCEP ATP III) and the International Diabetes Federation (IDF) definitions. Results: Significant ethnic differences (P < 0.01) in classification were noted for both metabolic syndrome definitions (NCEP ATP III, CA = 16.7% vs. AA = 5.7%; IDF, CA = 23.5% vs. AA = 8.2%). Ethnic differences were eliminated when fitness level or percent body fat was included as a criterion. Conclusions: If diagnosis of metabolic syndrome is intended for early recognition of CVD risk and slowing CVD development, current definitions for metabolic syndrome will not capture healthy AA. Health-care providers may consider assessing percent body fat and participation in regular exercise, because these criteria would help identify AA at risk.