Mortality of South Asian patients with insulin-treated diabetes mellitus in the United Kingdom: a cohort study.

AIMS: To investigate mortality in South Asian patients with insulin-treated diabetes and compare it with mortality in non South Asian patients and in the general population. METHODS: A prospective cohort study was conducted of 828 South Asian and 27 962 non South Asian patients in the UK with insulin-treated diabetes diagnosed at ages under 50 years. The patients were followed for up to 28 years. Ethnicity was determined by analysis of names. Standardized mortality ratios (SMRs) were calculated, comparing mortality in the cohort with expectations from the mortality experience of the general population. RESULTS: SMRs were significantly raised in both groups of patients, particularly the South Asians, and especially in women and subjects with diabetes onset at a young age. The SMRs for South Asian patients diagnosed under age 30 years were 3.9 (95% CI 2.0-6.9) in men and 10.1 (5.6-16.6) in women, and in the corresponding non South Asians were 2.7 (2.6-2.9) and 4.0 (3.6-4.3), respectively. The SMR in women was highly significantly greater in South Asians than non South Asians. The mortality in the young-onset patients was due to several causes, while that in the patients diagnosed at ages 30-49 was largely due to cardiovascular disease, which accounted for 70% of deaths in South Asian males and 73% in females. CONCLUSIONS: South Asian patients with insulin-treated diabetes suffer an exceptionally high mortality. Clarification of the full reasons for this mortality are needed, as are measures to reduce levels of known cardiovascular disease risk factors in these patients.