Background: Three-year follow-up outcomes in diabetic patients after SES or PES implantation have not been reported. The purpose of this study was to compare the rate of major adverse cardiovascular event (MACE) (death, nonfatal myocardial infarction [MI], target lesion revascularization [TLR]) and to determine the predictors of MACEs after either sirolimus-eluting stent (SES) or paclitaxel-eluting stent (PES) implantation in diabetic patients during 3-year follow-up. Methods: Diabetic patients with de novo coronary lesions (169 patients with 190 lesions) were randomly assigned prospectively to either SES or PES in 6 different cardiovascular centers. Results: Baseline clinical and angiographic characteristics were similar between the 2 groups. The rates of MACEs (5.9% [n=5] in the SES vs. 9.5% [n=8] in the PES Group, p=0.374) and definite stent thrombosis (1.2% [n=1] in the SES vs. 3.6% [n=3] in the PES Group, p=0.368) were similar between the 2 groups during the 3-year follow-up. Multivariate logistic analysis showed that insulin treatment was the only independent predictor of MACE (odds ratio [OR] 8.60, 95% confidence interval [CI] 3.25 to 22.76, p < 0.001), TLR (OR 5.19, 95% CI 1.22 to 22.09, p = 0.026), and TVR (OR 9.50, 95% CI 3.07 to 29.44, p < 0.001) during the 3-year follow-up. Conclusions: The use of either SESs or PESs was effective in reducing MACEs (death, nonfatal MI, TLR), TVR, and stent thrombosis during the 3-year follow-up. Moreover, insulin treatment was a main predictor of TLR, TVR, and MACEs during the 3-year follow-up after either SES or PES implantation.