The increased risk of microvascular complications in South Asians with type 1 diabetes is influenced by migration

Aim We aimed to explore the association between South Asian ethnicity and complications of type 1 diabetes, and whether this is affected by migration. Methods In this retrospective cohort study, data on diabetes control and complications were obtained for South Asians in India (South Asians(India), n = 2592) and the UK (South Asians(UK), n = 221) and white Europeans in the UK (n = 1431). Multivariable logistic regression was used to identify associations between ethnicity and diabetic kidney disease, retinopathy and neuropathy adjusting for age, sex, BMI, disease duration, HbA(1c), blood pressure (BP) and cholesterol. Results South Asians(India) had significantly greater adjusted odds of diabetic kidney disease [odds ratio (OR) 5.0, 95% confidence intervals (CI) 3.6-7.1] and retinopathy (OR 1.8, 95% CI 1.2-2.5), but lower odds of neuropathy (OR 0.5, 95% CI 0.4-0.6) than white Europeans. South Asians(India) had significantly greater adjusted odds of diabetic kidney disease (OR 3.0, 95% 1.8-5.3) than South Asians(UK), but there was no significant difference in the odds of other complications. Conclusions In this hypothesis-generating study, we report that South Asian ethnicity is associated with greater risk of diabetic kidney disease and retinopathy, and lower risk of neuropathy than white European ethnicity. Part of the excess diabetic kidney disease risk is reduced in South Asians(UK). These associations cannot be accounted for by differences in vascular risk factors. Our findings in South Asians with type 1 diabetes mirror previous findings in type 2 diabetes and now need to be validated in a study of the effect of ethnicity on type 1 diabetes complications where healthcare is provided in the same setting.