Objectives: We evaluated the benefit of extended clopidogrel use on long-term risks of stent thrombosis (ST) and cardiovascular events in diabetic patients treated with drug-eluting stents (DES). Background: Diabetic patients have higher risks of long-term complications after coronary intervention. Data are limited regarding the effects of clopidogrel continuation, beyond 12 months, on late clinical events after DES implantation in diabetic patients. Methods: We identified 865 diabetic patients who underwent DES implantation between February 21, 2003 and March 16, 2006. A total of 802 patients surviving 12 months without adverse cardiovascular events (myocardial infarction [MI], ST, and any revascularization) were analyzed according to clopidogrel continuation at 12 months after the procedure. Outcomes of interest were ST, death, MI, and death or MI up to 4 years. Results: Patients with extended use of clopidogrel beyond 12 months had more complex clinical and angiographic characteristics as compared to those with clopidogrel use for < 12 months. After adjustment by baseline risk profile, extended clopidogrel beyond 12 months was not associated with a reduced risk of ST (hazard ratio [HR] 1.87, 95% confidence interval [CI] 0.56 to 6.32) during the 4 years of follow-up. In addition, the adjusted risks of death (HR: 1.03, 95% CI: 0.51 to 2.08) and death or MI (HR: 1.18, 95% CI: 0.61 to 2.29) were similar in the two groups. Conclusion: In diabetic patients treated with DES, extended continuation of clopidogrel beyond 12 months did not appear to reduce ST and death or MI during 4 years of follow-up.