Patients with diabetes mellitus are at increased risk for repeat interventions and mortality after coronary angioplasty and stenting. The efficacy of sirolimus-eluting stents (SESs) to improve the outcomes of these patients is a focus of interest. In the first 1,407 patients treated with SESs at our institution, 492 were diabetic (insulin dependent diabetes mellitus [IDDM], n = 160 and non-insulin-dependent DM [NIDDM], n = 332). The in-hospital and 1- and 6-month clinical outcomes were compared with those of 915 patients without DM (non-DM). The baseline characteristics were similar, except for more women, obesity, previous myocardial infarction, coronary artery bypass grafting, and renal insufficiency in the DM group (p <0.001). Compared with non-DM patients, DM patients had higher in-hospital (p <0.05) and 1-month mortality (p = 0.02). IDDM patients had more in-hospital renal failure (p = 0.04) and Q-wave myocardial infarctions (1.6% vs 0%, p = 0.04) compared with NIDDM patients, and higher mortality (3.1% vs 0.8%, p = 0.04) and subacute stent thromboses (2.3% vs 0.5%, p = 0.07) than non-DM patients at 30 days. At 6 months, DM patients had a higher incidence of Q-wave myocardial infarction, target lesion revascularization-major adverse cardiac events, and composite of death and Q-wave myocardial infarction than non-DM patients (6.0% vs 2.7%, p = 0.01). Late outcomes between the IDDM and NIDDM groups were similar. Multivariate analysis showed diabetes and acute renal failure as independent predictors of target lesion revascularization-major adverse cardiac events. In conclusion, our data showed that, despite a reduction in repeat revascularization, coronary intervention with SESs in diabetic patients is limited by higher mortality at 1 month and a higher incidence of Q-wave myocardial infarction and target lesion revascularization-major adverse cardiac events at 6 months compared with non-DM patients. Careful surveillance is required in IDDM patients undergoing SES implantation.