Objective：To investigate the effects of type 2 diabetes on postoperative acute renal injury （AKI） and other complications of off-pump coronery artery bypass grafting（OP-CABG）. Methods：Retrospectively analysed 894 cases of patients with OP-CABG from January 2012 to September 2017 in our hospital，including 318 patients with diabetes mellitus（DM）and 576 patients without DM. The statistical differences was analyzed using Graphpad Prism. Results：In total 894 patients of this study，there were significant differences in serum creatinine（SCr），glomerular filtration rate（eGFR），and creatinine clearance（CCr）after surgery between two groups. At 48h，SCr has the highest T-value（t=3.36）and P < 0.01. The intra-group mean of SCr was the highest at 12 h，and the deviation showed a significant increase，while the majority of patients fell back to preoperative level at 48h. Even in some patients，CCr，SCr and eGRF were smaller than preoperative values after coronary artery bypass surgery. Conclusion：Compared to patients without DM，patients with DM were more prone to AKI after OP-CABG，which appeared most at 12 h after surgery and had significant inter-group and intra-group difference in this time. Individual kidney showed a trend of deterioration or heal. In the two groups，the process of the AKI was not parallel to the process of systemic inflammatory response. The former healed at 48 h，while the latter continued to be aggravated.