People of South Asian descent have an increased risk of cardiovascular disease (CVD) and diabetes, but little is known about
the microcirculation in South Asian people despite evidence that this plays an important role in the aetiology of CVD. We
compared the retinal microcirculation in a population-based sample of 287 middle-aged adults (144 European 143 South
Asian) matched for age and sex. Retinal photographs were taken and analysed using a validated semi-automated program
and microvascular measures were compared. Blood pressure, anthropometry and fasting bloods were also measured. South
Asians had significantly fewer arteriolar and venular vessels and bifurcations. Arterioles and venules were longer and
venules were also more tortuous in South Asians. These differences were not explained by adjustment for traditional risk
factors including blood pressure, body mass index, diabetes or measures of insulin resistance. People of South Asian
descent have rarefaction of the retinal microcirculation compared to age-sex matched individuals of European descent.
Reduced microvascular density could contribute to the elevated risk of CVD and impaired glucose tolerance in South Asian
people.