Impact of metabolic syndrome independent of insulin resistance on the development of cardiovascular disease.

BACKGROUND  It is controversial as to whether metabolic syndrome is a predictor of cardiovascular disease (CVD) independent of insulin resistance (IR). The aim of this study was to determine the independent and combined effects of metabolic syndrome and IR on the incidence of CVD in a prospective cohort study. METHODS AND RESULTS  A total of 6,430 healthy subjects who underwent a health check-up were enrolled. Risk factors for atherosclerotic CVD (ASCVD) including ischemic heart disease (IHD) and stroke were measured. The prevalence of metabolic syndrome and IR were 24.4% and 25.6%, respectively. There were 644 incident cases (9.0%) of ASCVD diagnosed in the cohort. After adjusting for traditional confounders and IR, metabolic syndrome was related to the incidence of CVD. In the multivariate model, the hazard ratios (95% confidence intervals) of metabolic syndrome for IHD, stoke, and ASCVD were 1.66 (1.32-2.09), 1.60 (1.21-2.12), and 1.61 (1.36-1.90), respectively. The risk of IHD, stoke, and ASCVD increased with increasing number of metabolic syndrome components. Furthermore, the risk of CVD was stronger in those who had both metabolic syndrome and IR concurrently. CONCLUSIONS  Metabolic syndrome is related to the incidence of CVD independent of IR. Also, the combined effect of metabolic syndrome and IR contributes to the risk of CVD.