Prevalence and Determinants of Diabetic Retinopathy and Cataracts in West African Type 2 Diabetes Patients

Objective: To quantify the prevalence of, and risk factors for, diabetic retinopathy and cataracts in patients with type 2 diabetes, and their spouse controls, enrolled from 5 centers in 2 West African countries (Ghana and Nigeria).

Method: The analysis cohort was made up of 840 subjects with type 2 diabetes, and their 191 unaffected spouse controls, who were enrolled and examined in Lagos, Enugu, and Ibadan, in Nigeria, and in Accra and Kumasi, in Ghana. A diagnosis of diabetic retinopathy was made only where a participant had a minimum of one microaneurysm in any field, as well as exhibiting hemorrhages (dot, blot, or flame shaped), and maculopathy (with or without clinically significant edema).

Results: Average duration of diabetes was 7.0 years, and mean age at diagnosis was 46.5 years. Prevalence of diabetic retinopathy was 17.9%. Cataracts were present in 44.9% of the patients with type 2 diabetes, and in 18.3% of spouse controls. The risk of developing retinopathy increased more than 3-fold for patients at the highest fasting plasma glucose (FPG) level (OR=3.4; 95% CI, 1.8-6.3), compared to patients at the lowest FPG level. The odds ratios for persons with diabetes for 10 years or more, compared to persons with diabetes for less than 5 years, was 7.3 (95% CI, 4.3-12.3) for retinopathy, and 2.6 (95% CI, 1.5-4.5) for cataracts.

Conclusions: Cataracts were a more important cause of vision impairment than was diabetic retinopathy in this cohort. The prevalence of cataracts in patients with diabetes was more than twice that of their spouse controls, indicating that type 2 diabetes is an important risk factor for cataract formation. Individuals who developed type 2 diabetes at an earlier age were more likely to develop both diabetic retinopathy and cataracts. A strong positive association was observed between FPG level, duration of diabetes, and risk of retinopathy and cataracts. The low prevalence of retinopathy and cataracts observed within the first 5 years of diagnosis of diabetes in this cohort, suggests that intensive blood glucose control may reduce the risk of the development and progression of retinopathy and cataracts. In this regard, early eye examination, preferably at first presentation of elevated blood glucose, is highly recommended.