Background: Diabetes is a well-known risk factor for coronary artery disease and cardiovascular death. The reported prevalence of diabetes among patients undergoing coronary artery bypass surgery (CABG) has been estimated to be 12-38%. Patient and Methods: The impact of diabetes on early and midterm follow-up after coronary artery bypass grafting was studied by comparing the outcomes between 50 patients without diabetes mellitus and 50 patients with type II Diabetes Mellitus from March 2013 till December 2014. Results: Compared with nondiabetic patients, the group with diabetes hada greater incidence of hypertension (70% in diabeticsvs 42% in non-diabetics, P=0.004) and hyperlipidemia, showed a higher incidence of ECG changes (previous myocardial infarction, ST‐T changes and conduction defects) (72% in diabetics vs. 44% in non-diabetics, P=0.005). Early mortality was not significantly different between two groups (2% in diabetics vs. 2% in non-diabetics, P=0.661). No significant differences were found regarding postoperative complications; except sternal wound infection (12% in diabetics vs. 2% in non-diabetics, P=0.049). However, in midterm follow up of diabetic patients had significantly higher MACCE (16.4% in diabetics vs. 4% in nondiabetics, P= 0.04). Conclusion: Except for sternal wound infection, DM was not associated with the in- hospital adverse outcomes in the patients undergoing isolated CABG. Diabetes mellitus is an independent predictor of adverse cardiac and cerebrovascular events after isolated coronary artery bypass graft surgery (CABG).