Objective To investigate the coronary angiography characteristics of acute myocardial infarction (AMI) combined with diabetes mellitus (DM). Methods Forty-five AMI patients combined with DM and 45 AMI patients without DM all received coronary angiography and the results were compared retrospectively, then the differences of coronary angiography and electrocardiogram characteristics were analyzed. Results The ratio of triple vessel lesions and diffuse lesions of coronary artery were more higher in AMI patients combined with DM than those in AMI patients without DM [64.4%(29/45) vs 35.6%( 16/45) and 82.2%(37/45)vs 40.0%(18/45),P< 0.05]. Non-ST segment elevation myocardial infarction (NSTEMI) was more common seen in AMI patients combined with DM than that in AMI patients without DM [37.8% (17/45)vs 17.8% (8/45),P<0.05]. Conclusion AMI patients combined with DM often have NSTEMI with triple vessel lesions and diffuse lesions of coronary artery.