Ethnic differences in diabetic retinopathy.

AIMS/HYPOTHESIS: To compare the prevalence of diabetic retinopathy in European, Maori and Pacific peoples with diabetes.
METHODS: Biomedical assessment and retinal examination, using photography where possible, was undertaken in 458 (67.5% of eligible) randomly selected household survey participants with known diabetes (168 Europeans, 144 Maori, 149 Pacific people). Glycaemia was measured by glycated haemoglobin, fructosamine and random glucose.
RESULTS: In those with Type 2 diabetes, the prevalence of moderate or more severe retinopathy was 4.0% in Europeans, 12.9% in Maori and 15.8% in Pacific people (P = 0.003). There was no significant ethnic difference in the prevalence of retinopathy overall or in that of macular disease. Cataracts were more common in Pacific people (19.3%, 16.4%, 36.6%, respectively, P < 0.001). After adjusting for diabetes duration and ethnicity, Type 1 diabetes was associated with 5.3(1.7-16.4)-fold increase in moderate or more severe retinopathy. Although Maori and Pacific people with Type 2 diabetes were more hyperglycaemic, with higher systolic and lower diastolic blood pressure, in the logistic regression analysis, moderate or more severe retinopathy was associated with diabetes duration, insulin therapy, ethnicity and the extent of renal disease, but not glycaemia.
CONCLUSIONS: These data demonstrate that moderate or more severe retinopathy is more common in Polynesians than Europeans. The reasons for this are unclear, but may be related to long-standing hyperglycaemia.