To evaluate the influence of type 2 diabetes mellitus on the long-term outcomes of Chinese patients with previous myocardial infarction, we studied 864 patients with previous myocardial infarction, including 251 with type 2 diabetes mellitus and 613 without type 2 diabetes mellitus, over a median follow-up time of 2.9 years. The type 2 diabetes mellitus patients were subdivided into 95 insulin-treated diabetes mellitus and 156 non-insulin-treated diabetes mellitus subjects. The crude incidences (per 1000 patient-years) in the type 2 diabetes mellitus subjects versus the non-type 2 diabetes mellitus subjects were 43.7 versus 25.1 for recurrent myocardial infarction, 68.7 versus 28.3 for all-cause death and 99.8 versus 49.9 for the composite end point (i.e. recurrent myocardial infarction or all-cause death). Cox regression analysis showed that the adjusted hazard ratios for recurrent myocardial infarction, all-cause death and their combination were 1.67 (95% confidence interval: 1.06–2.74), 1.90 (1.25–2.90) and 1.72 (1.23–2.40), respectively. Significant associations were also observed between insulin treatment and all-cause death. Our findings suggested that type 2 diabetes mellitus is an independent risk factor for recurrent myocardial infarction, all-cause death and the composite end point among previous myocardial infarction patients.