Objective: The study objective was to examine the influence of glycaemic control and ethnic variations on the incidence and progression of diabetic retinopathy (DR). Design, subjects and setting: Eight hundred and ninety-two persons with type 1 diabetes mellitus, and 1 998 persons with type 2 diabetes mellitus, who were enrolled in a private diabetes mellitus management programme in South Africa, participated in the study. Survival analyses were conducted to assess the relationship between the

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... isk factors and the incidence of DR and referable DR, and the progression of DR. Outcome measures: Cumulative incidence of diabetic retinopathy and referable diabetic retinopathy. Results: The seven-year cumulative incidence of DR and referable DR was 536 and 50 cases per 1 000 persons with type 1 diabetes mellitus without DR at baseline, and 351 and 47 cases per 1 000 persons with type 2 diabetes mellitus. The seven-year cumulative incidence of referable DR was 332 cases per 1 000 persons with type 1 diabetes mellitus with background DR at baseline, and 360 cases with type 2 diabetes mellitus, representing a seven-and eightfold increase compared to no DR at baseline. After controlling for known risk factors for DR, a high baseline haemoglobin A 1c (HbA 1c ) and non-Caucasian ethnicity were associated with the incidence of referable DR in patients with type 1 and type 2 diabetes mellitus. Conclusion: It was revealed in the first study to report on the incidence and progression of DR in South Africa that a high baseline HbA 1c, ethnicity, and the presence of background DR increased the risk of the development of referable DR.