BACKGROUND: It remains controversial whether body mass index (BMI), waist circumference (WC), or waist-hip ratio (WHR) is a better risk predictor of type 2 diabetes. OBJECTIVE: The objective was to examine the sex-specific relevance of WC, WHR, and BMI to the development of type 2 diabetes. DESIGN: The prospective population-based cohort study was based on 3055 men and 2957 women aged 35-74 y who participated in the second (1989-1990) or third (1994-1995) MONICA (Monitoring Trends and Determinants on Cardiovascular Diseases) Augsburg survey. The subjects were free of diabetes at baseline. Hazard ratios (HRs) were estimated from Cox proportional hazards models. RESULTS: During a mean follow-up of 9.2 y, 243 cases of incident type 2 diabetes occurred in men and 158 occurred in women. Multivariable-adjusted HRs across quartiles of BMI were 1.0, 1.37, 2.08, and 4.15 in men and 1.0, 3.77, 4.95, and 10.58 in women; those of WC were 1.0, 1.15, 1.57, and 3.40 in men and 1.0, 3.21, 3.98, and 10.70 in women; those of WHR were 1.0, 1.14, 1.80, and 2.84 in men and 1.0, 0.82, 2.06, and 3.51 in women. In joint analyses, the highest risk was observed in men and women with a high BMI in combination with a high WC and a high WHR. CONCLUSIONS: Both overall and abdominal adiposity were strongly related to the development of type 2 diabetes. Because there was an additive effect of overall and abdominal obesity on risk prediction, WC should be measured in addition to BMI to assess the risk of type 2 diabetes in both sexes.