ETHNIC-DIFFERENCES IN THE CLINICAL AND LABORATORY ASSOCIATIONS WITH RETINOPATHY IN ADULT-ONSET DIABETES - STUDIES IN PATIENTS OF AFRICAN, EUROPEAN AND INDIAN ORIGINS

Objective. To evaluate the prevalence of diabetic retinopathy (DR) and its associations in adult onset diabetic patients of African, Europea n and Indian origins. Design. The prevalence of retinopathy was determ ined by 60 degrees retinal photography in 507 consecutive out-patients . Clinical and laboratory associations were evaluated. Setting. Diabet es clinic in a large community hospital. Main outcome measures. The as sociations between clinical and laboratory measurements with retinopat hy. Results. African patients (A) had shorter duration of diabetes (P < 0.001), higher HbA1 levels (P < 0.01) compared to those of Europeans (E) and Indian (I) extraction. A also had lower C-peptide levels (med ian 0.57 nmol L(-1); vs. E, 0.81 nmol L(-1) and I, 0.93 nmol L(-1)) (P < 0.001). The prevalences of retinopathy at diagnosis (21-25%) and ov erall were similar (A 37%, E 41%, I 37%). Severe DR was more frequent in the Africans (52%, P < 0.0001) and Indians (41%, P = 0.03) compared to the Europeans (26%). In Africans DR was significantly associated o nly with duration of diabetes (P < 0.0001) and macro-albuminuria (P = 0.01); in I it was also associated with systolic BP (P = 0.03); in E a lso with lower C-peptide levels (P = 0.0002), worse glycaemic control and greater use of insulin (P < 0.0001). In patients with DR insulin w as used less frequently in A (35%) than in E patients (62%) (P = 0.001 ). Conclusions. In South Africa, the African population with adult ons et diabetes has the highest prevalence of severe retinopathy, probably the result of very poor glycaemic control attributable to more severe insulinopenia and infrequent insulin treatment. Visual loss from diab etic retinopathy is likely to be considerable in Africans.