Diabetes mellitus has become a growing epidemic in the Asia-Pacific region. The aims of this study were to determine at autopsy the prevalence and characteristics of pathologic lesions in patients with diabetes mellitus. The 13,215 autopsy reports in our institution were examined for the diagnosis of diabetes mellitus. In patients with diabetes mellitus, the demographic data and the different pathologic lesions noted were analyzed. Diabetes mellitus was found in 820 patients (426 men and 394 women), comprising 6.2% of all autopsies. The two most common types of disease were cardiovascular diseases and infections, found in 69 and 53% of diabetic patients, respectively. Bacterial infection, in particular tuberculosis, was the most common type of infection noted. Localized and disseminated fungal infections were also common. In addition, urinary tract diseases were noted in 48%, hepatobiliary tract lesions in 42%, central nervous system disorders in 25%, and tumors in 29% of the diabetic patients. Malignant tumors were more often seen than benign tumors (18 vs 11% of patients, respectively). Many of the tumors were adenocarcinomas, and the most common neoplastic lesions were carcinomas of the lung, pancreas, liver, large intestine, stomach, and esophagus. Diabetic complications and associated diseases are common problems in this population. Adequate health care resources are needed for their prevention and treatment.