A proposal for the cutoff point of waist circumference for the diagnosis of metabolic syndrome in the Japanese population.

O ver the past 2 decades, there has been a dramatic increase in the number of subjects with the metabolic syndrome in Japan as well as in Western countries. Because subjects with the metabolic syndrome have an elevated risk of development of type 2 diabetes and cardiovascular diseases (1–3), there is an urgent need to establish strategies to prevent an epidemic of this syndrome. In particular, a practical and sensitive screening system must be established to detect the metabolic syndrome. At present, there are two internationally recognized definitions of the metabolic syndrome, namely those of the World Health Organization (4) and the National Cholesterol Education Program’s Adult Treatment Panel III (NCEP III) (5). In an attempt to establish a unified definition for the metabolic syndrome, the International Diabetes Federation (IDF) has very recently announced a new definition of the metabolic syndrome that is expected to be suitable for use in clinical practice worldwide (6). The IDF defines metabolic syndrome as the presence of central obesity plus any two of the following four factors (raised triglyceride level, reduced HDL cholesterol, raised blood pressure, and raised fasting plasma glucose). The IDF recommended that the cutoff level used for the waist circumference to define central obesity should be different among different ethnic groups (7). In fact, the new IDF definition has proposed ethnicity-specific cutoff values for waist circumference, namely, 94 and 80 cm for European men and women, respectively, and 85 and 90 cm for Japanese men and women, respectively. Nonetheless, the IDF has strongly recommended that more extensive investigations should be performed before suitable cutoff levels are established for use in clinical practice (7). In this study, we investigated the relationship between the cutoff values used for the waist circumference to define central obesity and rates of detection of subjects having multiple risk factors of the metabolic syndrome and attempted to determine the most suitable cutoff level of waist circumference for the diagnosis of metabolic syndrome in a communitybased cohort.