Regardless of central obesity, metabolic syndrome is a significant predictor of type 2 diabetes in Japanese Americans

AIMS/INTRODUCTION: The impact of metabolic syndrome (MetS) on the development of type 2 diabetes has been reported in different ethnic populations. However, whether central obesity is an essential component as a diagnostic criterion for MetS remains a controversial topic. The aim of the present study was to investigate the association between MetS and the incidence of type 2 diabetes with or without central obesity in a Japanese American population. MATERIALS AND METHODS: We examined whether MetS predicts incident type 2 diabetes among 928 Japanese American participants who did not have diabetes enrolled in an ongoing medical survey between 1992 and 2007. MetS was defined on the basis of American Heart Association/National Heart, Lung, and Blood Institute criteria. The average follow-up period was approximately 6.8 years. RESULTS: During the follow-up period, 116 new cases of diabetes were diagnosed. Compared to the participants without MetS, the hazard ratio (HR) for incident type 2 diabetes was significantly higher in participants with MetS, after adjustment for sex, age and impaired glucose tolerance (HR 1.64, 95% CI 1.11–2.42). The risk of type 2 diabetes was found to be significantly higher in participants with MetS but without central obesity (HR 2.07, 95% CI 1.25–3.41), as well as in participants with MetS and with central obesity (HR 2.46, 95% CI 1.51–4.01) than in participants with neither MetS nor central obesity, after adjustment for sex, age and impaired glucose tolerance. CONCLUSIONS: These results show that the presence of MetS, with or without central obesity, could independently predict the development of type 2 diabetes in Japanese Americans.