Objective:To investigate the clinical characteristics of malignant tumor with type 2 diabetes mellitus. Methods:We assembled a cohort of 201 dead patients from 2000 to 2005 who were diagnosed type 2 diabetes mellitus,and identified those who developed cancer at least six months after meeting criteria for diabetes. We analysed the distribution of malignant tumor in different systems and in various ages. Results:Of 201 diabetic subjects(75 female,126 male), 57 patients were diagnosed carcinoma. The group of 40~55 years were less likely to have cancer,and much more to use metformin. A larger proportion of those who developed malignant tumors were males. The probability of cancer in digestive system,blood system,respiratory system and urinary system went down sequencely. Cancer were identified in different time after the date diabetes criteria were met in different systems:only about 3 years of pancreatic cancer, about 11 years of colonic cancer and lung cancer, and the middle of other cancers. Conclusion:The incidence of cancer among persons with diabetes was significantly correlated with age and sex. The distributing characteristics of carcinoma associated with diabetes were different in different systems. Metformin may be associated with a decrease in risk of cancer of diabetes patients. But the dead ages of diabetes subjects with and without cancer were not different which need further researches.