Objective To investigate the appropriate waist circumference (WC) cutoff points for central obesity in the middle-aged and elderly Beijing residents by the metabolic syndrome definition of the International Diabetes Federation (IDF). Methods A total of 2,344 Beijing residents aged ≥40 years were investigated. They answered questionnaires, received physical examinations, and underwent plasma glucose and lipid profile measurement. Those non-diabetic subjects underwent a 75g oral glucose tolerance test. All data were analyzed to calculate the appropriate WC cutoff points for central obesity reaching the diagonsis of MS. Results 1) Both in males and females, the triglyceride (TG), systolic blood pressure, diastolic blood pressure and fasting plasma glucose (FPG) increased linearly with WC, and the high density lipoprotein cholesterol (HDL-C) decreased linearly with WC (P<0.05). 2)The prevalence of elevated TG, reduced HDL-C, elevated blood pressure, elevated FBG, or ≥ 2 of these factors increased with WC (P<0.05). 3) Based on the receiver operating characteristic (ROC) curve analysis and Youden index, the WC values for central obesity and for detecting BMI ≥ 25 kg/m2 were about 90 cm for men and 80 cm for women. 4) The odds ratio for the presence of two or more metabolic risk factors increased abruptly in men with WC ≥ 90 cm and in women with WC ≥ 80 cm. Conclusions The appropriate WC cutoff point for central obesity was determined to be 90 cm for men and 80 cm for women in the middle-aged and elderly Beijing residents by the metabolic syndrome definition of IDF. Objective To investigate the appropriate waist circumference (WC) cutoff points for central obesity in the middle-aged and elderly Beijing residents by the metabolic syndrome definition of the International Diabetes Federation (IDF). Methods A total of 2,344 Beijing residents aged ≥40 years were They said questionnaires, received physic examinations, and underwent plasma glucose and lipid profile measurement. Those non-diabetic subjects underwent a 75g oral glucose tolerance test. All data were analyzed to calculate the appropriate WC cutoff points for central obesity reaching the diagonsis of MS. Results 1) Both in males and females, the triglyceride (TG), systolic blood pressure, diastolic blood pressure and fasting plasma glucose (FPG) increased linearly with WC, and the high density lipoprotein cholesterol (HDL-C) decreased linearly with WC (P <0.05). 2) The prevalence of elevated TG, reduced HDL-C, elevated blood pressure, elevated FBG, or ≧ 2 of these factors 3) Based on the receiver operating characteristic (ROC) curve analysis and Youden index, the WC values ​​for central obesity and for detecting BMI ≥ 25 kg / m2 were about 90 cm for men and 80 cm for women. 4) The odds ratio for the presence of two or more metabolic risk factors increased abruptly in men with WC ≥ 90 cm and in women with WC ≥ 80 cm. Conclusions The appropriate WC cutoff point for central obesity was determined to be 90 cm for men and 80 cm for women in the middle-aged and elderly Beijing residents by the metabolic syndrome definition of IDF.