To determine whether the higher prevalence of diabetes found among blacks in the United States is explained by racial differences in obesity, we examined the prevalence of diabetes adjusted for adiposity, education, and income in a cohort of US Army veterans from the Vietnam era. Among 12 558 white men and 1677 black men, aged 30 to 47 years, blacks were more likely than whites to have diagnosed diabetes (adjusted prevalence ratio, 1.9; 95% confidence interval, 1.3 to 2.7). Within every age, adiposity, and socioeconomic stratum, blacks had a higher prevalence of diagnosed diabetes than whites. In a subgroup of veterans for whom fasting serum glucose values were measured, blacks were more likely than whites to have fasting hyperglycemia (fasting serum glucose value≥7.8 mmol/L) (adjusted prevalence ratio, 5.7; 95% confidence interval, 2.7 to 12.0). These data provide evidence that the higher prevalence of diabetes found among blacks is not explained by differences in obesity.