Background and methods: Diabetes mellitus is still potent deteriorative factors in coronary atherosclerosis or restenosis even after implantation of drug-eluting stent (DES). Long-term clinical outcomes after drug-eluting stent in patients with diabetes mellitus are still controversial according to the therapeutic modality. From 2003 to 2008, total 793 patients of PCI with DES was followed-up and retrospectively analyzed for major cardiac adverse events and hospitalization for any causes. By its treatment strategy for diabetes, we have divided these patients in two groups (group 1 : Oral agent only, 670 patients, group 2 : Insulin therapy with or without oral agent, 123 patients) Baseline and clinical characteristics showed similar result for in-stent restenosis (14.9% in group1 vs. 10.6% in group 2, p=0.21), however, minimum value of fasting glucose (134.5짹42.0 mg/dl vs. 158.5짹78.2 mg/dl, p<0.001) and glycated hemoglobin showed statistically higher in Group 2 (7.3짹1.5% vs. 8.0짹1.46%, p<0.001). Survival analysis according to the major adverse cardiac event (MACE) including death, myocardial infarction, target lesion or vessel revascularization showed higher in group 1 (21.1% vs. 13.9%, p=0.049). In addition, total hospitalization for any causes showed significantly higher in group 2 especially due to sugar control and complication management (52.8% vs. 40.3%, p=0.005) Cox regression hazard model showed insulin treatment is the only meaningful predictor for hospitalization free survival (HR 1.38, 95% CI 1.017 to 1.875, p=0.039). Conclusion : Strict sugar control after drug-eluting stent should not be underestimated even after confirmation of stent patency or symptom free status.