Objective: Metabolic syndrome is diagnosed according to several criteria. Of these, some require glucose intolerance and others require obesity for the diagnosis. We investigated the relationship between metabolic risk factor clustering and cardiovascular disease (CVD) mortality stratified by high blood glucose or obesity.
Research design and methods: We followed 7,219 Japanese men and women without a history of CVD for 9.6 years. We defined high blood pressure, high blood glucose, high triglycerides, low HDL cholesterol, and obesity as metabolic factors. The multivariate adjusted hazard ratio (HR) for CVD mortality according to the number of clustering metabolic factors was calculated using the Cox proportional hazards model.
Results: During follow-up, 173 participants died of CVD. The numbers of metabolic risk factors and CVD mortality were positively correlated (P(trend) = 0.07). The HR was obviously higher among participants with than among those without high blood glucose and clustering of > or =2 other metabolic risk factors (HR 3.67 [95% CI 1.49-9.03]). However, the risk increase was only modest in participants without high blood glucose even if they had > or =2 other metabolic risk factors (1.99 [0.93-4.28]). Conversely, metabolic risk factor clustering was related to CVD mortality irrespective of obesity.
Conclusions: Our findings suggest that glucose tolerance plays an important role in CVD mortality. Because the prevalence of nonobese participants with several metabolic risk factors was quite high and their CVD risk was high, excluding them from the diagnosis of metabolic syndrome because of the absence of obesity might overlook their risk.