Evaluation of risk for metabolic syndrome according to the fasting insulin concentration in Korean men

Background As a well-known risk factor for cardiovascular disease, metabolic syndrome (MetS) is an important global health problem due to its high worldwide prevalence. The objective of this study is to determine whether the fasting serum insulin concentration influences future incidence of MetS. Methods A total of 14,621 Korean men without MetS participating in a medical health check-up program were followed up from 2005 until 2010. They were divided into 4 groups according to baseline fasting insulin concentrations. The incidence of MetS was compared among the groups, and Cox proportional hazards model was used to determine if MetS was associated with higher fasting insulin concentration. Results The incidence of MetS increased according to the baseline fasting insulin concentration (first quartile: 8.4%, second quartile: 12.3%, third quartile: 16.3%, fourth quartile: 26.5%, P < 0.001). Even after adjusting for multiple covariates, the hazard ratio (95% CI) for MetS was higher for the second (1.13 (0.93–1.37)), third (1.29 (1.06–1.56)) and fourth quartile group (1.70 (1.36–2.13)), compared to the first quartile group (P for trend < 0.001). Conclusion The incidence of MetS increased proportionally to fasting insulin concentration. Additionally, increased fasting insulin concentration was an independent risk factor for the future development of MetS.