Objective To examine the effects of diabetes on coronary heart disease, ischemic and hemorrhagic stroke and cardiovascular disease according to category of body mass index. Methods Data on 161,161 men and women from 31 cohorts (baseline years, 1966–99; mean follow-up, 2–24 years) from the Asia Pacific Cohort Studies Collaboration were analyzed using Cox regression, stratified by sex and study and adjusted for age, systolic blood pressure and smoking. Diabetes was self-reported in all but one study. Body mass index was divided into five categories according to the World Health Organization Asian criteria. Results The hazard ratio (diabetes v. not) for cardiovascular disease was 1.83 (95% confidence interval, 1.66–2.01). Across body mass index categories, this hazard ratio did not change significantly (p = 0.19). Similar lack of difference across body mass index groups was found for coronary heart disease (p = 0.33), ischemic stroke (p = 0.97) and hemorrhagic stroke (p = 0.98). Conclusions Body mass index does not modify the effect of diabetes on major cardiovascular outcomes.