Prevalence of metabolic syndrome and optimal waist circumference cut-off values in Japan.

The present study examined the prevalence of metabolic syndrome (MetS) when the Japanese diagnostic criteria was used, the prevalence of each component in the criteria, and also the validity of the waist circumference cut-off value measured at the navel level, using the results obtained from the Japanese National Health and Nutrition Survey (NHNS) in 2003. The prevalence of MetS in 2113 subjects according to the Japanese diagnostic criteria was 22.8% (95% CI: 20.2-25.5) for males and 8.7% (7.1-10.4) for females. The prevalence for high blood pressure (HBP), dyslipidemia (DLP), high fasting blood glucose (HFG) and central obesity for males/females were 59.1% (56.0-62.2)/47.2% (44.3-50.1), 40.5% (37.3-43.6)/27.9% (25.4-30.5), 19.1% (16.6-21.6)/16.2% (14.0-18.3) and 45.9% (42.7-49.0)/17.4% (15.3-19.5), respectively. The low prevalence of MetS for females was attributed to a larger waist circumference cut-off value for females (90 cm) than for males (85 cm). Optimal waist circumference cut-off values of subjects, who fulfil at least two of HBP, DLP or HFG, estimated from the receiver operating characteristic curve were subsequently found to be 85 cm for males and 80 cm for females. Based on the new values, the prevalence of MetS was found to be 22.8% for males and 19.2% for females. The present study revealed that optimal waist circumference cut-off value was much shorter than that previously proposed in females.