The effect of captopril on progression of retinopathy in type 2 diabetes

Background: Diabetic retinopathy is the leading cause of blindness in those of working age in the world. However, it is a preventable vision loss. According to current animal studies, it could be hypothesized that using angiotensin-converting enzyme inhibitors could play a crucial role as a protective factor in the progression of retinopathy in human. Because little known is about this effect in humans, we designed a case-control study to explore whether captopril could be a protective factor for prevention of retinopathy in patients with diabetes. Methods: A case-control study was conducted on 164 patients with type 2 diabetes. Thirty-three patients with retinopathy were considered as cases, and 41 patients, without retinopathy, were designated as controls. All biochemical data were collected from results of laboratory tests at the last clinical visit. Dilated eye examination was performed by a trained ophthalmologist using direct and indirect ophthalmoscopy on dilated pupils. Results: Retinopathy was determined to be 35.4% and occurred more in men. Older age, male sex, longer duration of diabetes, higher systolic blood pressure, uncontrolled diabetes, and lower body mass index were associated with retinopathy. In our model only age (odds ratio [OR] = 3.2, 95% confidence interval [CI] = 1.3-7.9) and hemoglobin A1c (HbA1c) (OR = 3.6, 95% CI = 1.3-9.9) were found to be associated with the risk of retinopathy. Forty-five percent had hypertension. Age (OR = 2.9, 95% CI = 1.8-4.7), duration of diabetes (OR = 2.4, 95% CI = 1.5-3.87), and HbA1c (OR = 3.73, 95% CI = 1.82-7.64) were associated with developing retinopathy in patients with diabetes and hypertension. However, captopril was shown to be a protective factor after adjusting other variables in our model. This effect was not statistically significant (OR = 1.5, 95% CI = 0.37-6.2). Conclusions: The benefit of using captopril to slow or prevent the progression of retinopathy has been demonstrated in this study. However, statistically it is very difficult to be confident in interpreting the results, and therefore more trials are needed.