Impaired post-ischaemic microvascular hyperaemia in Indian Asians is unexplained by diabetes or other cardiovascular risk factors.

OBJECTIVE: People of Indian Asian descent have an increased risk of cardiovascular disease (CVD) that cannot be explained by diabetes and other established CVD risk factors. We investigated if microcirculatory function was impaired in a population-based sample of people of Indian Asian descent compared with Europeans in the UK and whether any differences could be accounted for by diabetes or other CVD risk factors. RESEARCH DESIGN AND METHODS: Cutaneous microvascular function was assessed using laser Doppler fluximetry in response to heating to 42 °C (maximum hyperaemia) and 3 min arterial occlusion (post occlusive reactive hyperaemia: PORH) in 148 Indian Asians and 147 Europeans. Blood pressure, anthropometry and fasting bloods were also measured. RESULTS: Maximum hyperaemia and minimum resistance did not differ significantly by ethnicity. Resting flux and PORH were lower in Indian Asians and time to peak of PORH was prolonged. Diabetes was associated with reduced maximum hyperaemia and PORH. Adjustment for diabetes accounted for differences in resting flux and time to peak but not differences in PORH (Europeans = 45.0 (40.3, 50.1)au, Indian Asians = 35.6 (31.9, 39.7)au, mean (95% confidence interval); p = 0.008 after adjustment). Differences in conventional CVD risk factors did not account for interethnic differences in microvascular responses. CONCLUSIONS: People of Indian Asian descent have impaired post-occlusive reactive hyperaemia unexplained by diabetes, dysglycaemia or other CVD risk factors. Abnormal microvascular function in response to ischaemia could represent a novel mechanism contributing to the elevated risk of CVD in Indian Asians.