This study aimed to investigate the clinical characteristics of sudden death (SD) in type 2 diabetes mellitus (DM2). Clinical data from 1988 through 1996 in our hospital showed that 130 hospitalized patients with DM2 died, and 17 of them died of SD (13.08%). These 17 SD patients were pair-matched with 17 DM2 patients who were alive in the same period. The results revealed that the SD group had longer clinical DM duration, more chronic diabetic complications and higher blood pressure. In the direct causes of SD, cardiac SD accounted for 76.47%. The others were non-cardiac factors, including cerebral hemorrhage, hyperkalemia from diabetic nephropathy with renal failure and respiratory tract obstruction from lung infection. The triggering causes included eating, defecting, lung infection, strenuous attempt, hypoglycemia and surgical operation. To reduce the rate of SD in DM2, it is necessary and vital to treat the DM2 itself, and to take positive steps to prevent the onset of SD in high risk patients.