Mortality and causes of death in a national sample of type 2 diabetic patients in Korea from 2002 to 2013

Background: We aimed to investigate the mortality rate (MR), causes of death and standardized mortality ratio (SMR) in Korean type 2 diabetic patients from 2002 to 2013 using data from the Korean National Health Insurance Service-National Sample Cohort (NHIS-NSC). Methods: From this NHIS-NSC, we identified 29,807 type 2 diabetic subjects from 2002 to 2004. Type 2 diabetes was defined as a current medication history of anti-diabetic drugs and the presence of International Classification of Diseases (ICD)-10 codes (E11-E14) as diagnosis. Specific causes of death were recorded according to ICD-10 codes as the following: diabetes, malignant neoplasm, disease of the circulatory system, and other causes. Results: A total of 7103 (23.8 %) deaths were recorded. The MR tended to increase with age. In particular, the ratio of MR for men versus women was the highest in their 40s-50s. The overall SMR was 2.32 and the SMRs attenuated with increasing age. The causes of death ascribed to diabetes, malignant neoplasm, ischemic heart disease, cerebrovascular disease, and other causes were 22.0, 24.8, 6.2, 11.2 and 31.3 %, respectively. The SMRs according to each cause of death were 9.73, 1.76, 2.60, 2.04 and 1.89, respectively. Conclusions: The MRs among type 2 diabetic subjects increased with age, and diabetic men exhibited a higher mortality risk than diabetic women in Korea. Subjects with type 2 diabetes exhibited an excess mortality when compared with the general population. Approximately 78.0 % of the diabetes-related deaths was not ascribed to diabetes, and malignant neoplasm was the most common cause of death among those not recorded as diabetes.