Ethnicity and long-term vascular outcomes in Type 2 diabetes: a prospective observational study (UKPDS 83)

Evidence of ethnic differences in vascular complications of diabetes has been inconsistent. The aim of this study was to examine the relationship between ethnicity and long-term outcome in a large sample of individuals with newly diagnosed Type 2 diabetes.

In a prospective observational study of 4273 UK Prospective Diabetes Study participants followed for a median of 18 years, 3543 (83%) were White Caucasian, 312 (7%) Afro-Caribbean and 418 (10%) Asian Indian. Relative risks for predefined outcomes were assessed comparing Afro-Caribbean and Asian Indian with White Caucasian using accelerated failure time models, with adjustment for cardiovascular risk factors and other potentially confounding variables.

During follow-up, 2468 (58%) participants had any diabetes-related end point, 1037 (24%) a myocardial infarction and 401 (9%) a stroke, and 1782 (42%) died. Asian Indian were at greater risk (relative risk, 95% confidence interval) for any diabetes-related end point (1.18, 1.07-1.29), but at lower risk of all-cause mortality (0.89, 0.80-0.97) and peripheral vascular disease (0.43, 0.23-0.82), vs. White Caucasian. Afro-Caribbean participants were at lower risk for all-cause mortality (0.84, 0.76-0.93), diabetes-related death (0.75, 0.64-0.88), myocardial infarction (0.55, 0.43-0.71) and peripheral vascular disease (0.55, 0.33-0.93) vs. White Caucasian. No ethnicity-related associations were found for stroke or microangiopathy.

Asian Indian ethnicity is associated with the greatest burden of disease, but not with an increased risk of major vascular complications or death. Afro-Caribbean ethnicity is associated with reduced risk of all-cause and diabetes-related death, myocardial infarction and peripheral vascular disease, suggesting an ethnicity-specific protective mechanism.