Objective: To investigate the clinical characteristics of diabetic patients combined with acute myocardial infarction (AMI) and to compare the prognosis between diabetic and non- diabetic patients in 4-5 years after the onset of AMI. Methods: Followed the certain inclusive and exclusive criteria, a total of 420 patients with acute myocardial infarction were included and divided into diabetes group (group D) and non-diabetes group (group N) with numbers as 161 people and 259 respectively. Baseline data, clinical information, short-term outcome and long-term prognosis of the two groups were compared and analyzed. Results: Among the patients with diabetes, the average age was older (65.65±11.33 vs. 63.30±15.34), with fewer males (64.59% vs. 79.92%); and more likely to have other complications as hypertension (64.60% vs. 53.28%) or hyperlipidemia (42.24% vs. 26.25%). 59.29% of the patients in group D showed pathological changes in 3 major coronary arteries, which were significantly more than its counterpart (40.83%). The proportion of patients that had undergone the coronary artery bypass, grafting (11.11% vs. 5.31%) appeared also higher. There was no significant difference seen in the short-term outcomes between the two groups, but results from the long-term follow-up program showed that both the incidence of Major Adverse Cardiovascular Events (MACE) (50.67% vs. 27.72%) and the all-cause mortality (20.00% vs. 9.90%) in group D were higher than those appeared in group N (27.72%). Conclusions Patients suffered from the combination of both diabetes and acute myocardial infarction appeared older in age, more in females, with more complications and the coronary artery lesions were more severe and wider. During hospitalization, no significant difference was seen regarding the short-term outcomes between the two groups but the results from long-term follow-up process showing that the risk of MACE events was significantly higher in patients with type2 diabetes.