A sex × diabetes interaction in cardiovascular disease (CVD) has been established among white persons; however, it is unknown whether this interaction occurs among African Americans. We hypothesized that there was a multiplicative sex × diabetes interaction for CVD among African Americans participating in the Atherosclerosis Risk in Communities Study (1987-2013). Race-specific Cox models were run in three stages: Stage 1 examined baseline diabetes status; stage 2 examined baseline diabetes status with the competing risk of non-CVD death; and stage 3 examined time-varying diabetes status with a competing risk of non-CVD death. There were 1,073 incident CVD events among 3,767 African Americans and 2,475 among 10,291 white persons. Among African Americans, in stage 1 analysis, the hazard ratio for women with diabetes was 2.3 (95% confidence interval (CI): 2.0, 2.7) compared with women without diabetes after adjustment for age, and the corresponding hazard ratio for men was 1.8 (95% CI: 1.5, 2.1) (P for interaction = 0.014). After full adjustment, the diabetes hazard ratio was attenuated to 2.0 (95% CI: 1.8, 2.3) among women and remained 1.8 (95% CI: 1.5, 2.1) for men (P for interaction = 0.058). A synergistic influence on CVD risk between being a black woman and having diabetes was consistent across stage 2 and stage 3 analyses, with marginally significant interaction, mirroring sex differences seen in whites.