The relation between the abdominal accumulation of body fat, total-body adiposity, and blood glucose level and the risk of non-insulin-dependent diabetes mellitus was evaluated prospectively among 1,972 male participants in the Department of Veterans Affairs Normative Aging Study cohort. The risk of non-insulin-dependent diabetes mellitus was assessed by means of the proportional hazards model; 226 cases of diabetes occurred among the 1,972 men (mean age at entry, 41.9 years; range, 22-80 years) over 35,496 person-years of observation. The relation of body mass index to diabetes risk was partly explained by body fat distribution; after adjusting for age, the ratio of abdominal circumference to hip breadth, and cigarette smoking, men in the top tertile for body mass index had a 1.3-fold greater risk of diabetes than did men in the lowest tertile (95% confidence interval 0.9-1.8). Moreover, after adjusting for age, body mass index, and cigarette smoking, men in the top tertile for the ratio of abdominal circumference to hip breadth had a 2.4-fold greater risk of diabetes than did men in the lowest tertile (95% confidence interval 1.7-3.7). When blood glucose was analyzed as a continuous outcome variable, the findings were consistent, i.e., a positive association with abdominal fat independent of total-body adiposity. These results confirm previous reports of a prospective relation between abdominal adiposity and the risk of diabetes and provide prospective evidence of a relation between blood glucose levels and both body fat distribution and obesity.