Predictors of the incident metabolic syndrome in adults - The Insulin Resistance Atherosclerosis Study

OBJECTIVE- To prospectively investigate predictors of the incident metabolic syndrome in nondiabetic adults. RESEARCH DESIGN AND METHODS- This analysis included 714 white, black, and Hispanic participants in the Insulin Resistance Atherosclerosis Study (IRAS) who were free of the metabolic syndrome at baseline; 139 of these developed the metabolic syndrome in the subsequent 5 years. We examined measures of glucose (fasting and 2 h), insulin (fasting and 2 h, acute insulin response, insulin sensitivity [S-i], and proinsulin), lipids (HDL and triglycerides), blood pressure (systolic and diastolic), waist circumference, and baseline physical activity (total energy expenditure) as predictors of the metabolic syndrome. Logistic regression models were adjusted for age, sex, study site, ethnicity, and impaired glucose tolerance. Signal detection analysis was used to identify the characteristics of the highest risk group. RESULTS- The best predictors of incident metabolic syndrome were waist circumference (odds ratio [OR] 1.7 [1.3-2.0] per 11 cm), HDL cholesterol (0.6 [0.4-0.7] per 15 mg/dl), and proinsulin (1.7 [1.4-2.0] per 3.3 pmol/l). Signal detection analysis identified waist circumference (>89 cm in women, >102 cm in men) as the optimal predictor. CONCLUSIONS- These findings suggest that obesity may precede the development of other metabolic syndrome components. Interventions that address obesity and reduce waist circumference may reduce the incidence of the metabolic syndrome in nondiabetic adults.