Objective To study the impact of diabetes mellitus in elderly patients above sixty years old undergoing off-pump coronary artery bypass grafting. Methods Data were collected as part of prospective registry of off-pump coronary artery bypass grafting(OPCABG) from September 2009 to September 2010.One hundred and seventy-six patients were recruited.They were divided into diabetic group (n=86) and nondiabetic group(n=90) . Peroperative variables, such as age,EF and operative mortality, were compared between the two groups by univariate analysis or chi-square tests.Results The incidence of hyperlipidemia was higher in diabetic group than that in non-diabetic group,with significant difference (37.2% vs 17.8%，P <0.01). There was significant difference between the two groups in the number of affected coronary artery and the degree of lesion,especially the incidence of multi-branch lesion and diffuse lesion ,was higher than that in non-diabetic group. The rate of itraarotic ballon pumping (7% vs1.1%；P<0.05), the incidence of pulmonary infection (12.8% vs 4.4%，P<0.05) and the reuse of lifesaver(9.3% vs 2.2% P<0.05) were much higher in the diabetic patients. There was no significant difference in the duration of mechanical ventilation, ICU stay time, hospital stay time and in-hospital mortality between the two groups.  Conclusions Although the occlusion of the coronary arteries is severe, the therapeutic effect of OPCABG in diabetic senile patients is similar as that in patients without diabetes.