Incidence and Progression of Diabetic Retinopathy in Urban India: Sankara Nethralaya-Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS II), Report 1

Purpose: To evaluate the 4-year incidence and progression of and risk factors for diabetic retinopathy (DR) in an Indian population. Methods: From a cross-sectional study of 1425 subjects with diabetes, 911 (63.9%) returned for 4-year follow-up. After excluding 21 with ungradable retinal images, data from 890 subjects were analyzed. Participants underwent examinations based on a standard protocol, which included grading of retinal photographs. Results: The incidences of DR, diabetic macular edema (DME), and sight-threatening diabetic retinopathy (STDR) were 9.2%, 2.6%, and 5.0%, respectively. In subjects with DR at baseline, the incidence of DME and STDR had increased (11.5% and 22.7%, respectively). 1-step and 2-step progressions of DR were seen in 30.2% and 12.6% of participants, respectively, and 1-step and 2-step regressions were seen in 12.0% and 1.8%, respectively. Incident DR, DME, and STDR were associated with higher systolic blood pressure (odds ratio, OR, 1.21, 2.11 and 1.72, respectively, for every 10 mmHg increase). Incident DR and DME were associated with increasing duration of diabetes (OR 2.29 and 4.77, respectively, for every 10-year increase) and presence of anemia (OR 1.96 and 10.14, respectively). Incident DR was also associated with higher hemoglobin A1c (OR 1.16 for every 1% increase). Variables associated with 1-step progression were every 10 mg/dL increase in serum total cholesterol (OR 15.65) as a risk factor, and 10 mg/dL increase in serum triglyceride (OR 0.52) as a protective factor. Conclusions: The incidences of STDR and DME were higher in people with pre-existing DR than in those without DR at baseline.