Risk factors for diabetic retinopathy in a rural Chinese population with type 2 diabetes: the Handan Eye Study

Purpose: To describe risk factors associated with diabetic retinopathy (DR) in a population-based sample of rural Chinese with type 2 diabetes. Methods: The Handan Eye Study is a population-based cross-sectional study surveyed 6830 Chinese people aged 30+ years from 13 randomly selected villages in 2006-2007. All participants underwent a standardized interview and extensive examinations including ophthalmologic and systemic conditions. Diabetic retinopathy was graded from fundus photographs according to the modified Early Treatment Diabetic Retinopathy Study classification system. Logistic regression models were used to assess risk factors associated with DR. Results: Of 7577 eligible persons, 6830 (90.4%) participated, of which 5597 (81.9%) had fasting plasma glucose (FPG) data. There were 387 (6.9%) participants with diabetes, and 368 (95.1%) had gradable fundus photographs. The age-standardized prevalence of DR was 43.1%. In multivariable-adjusted logistic regression models for all diabetic participants, independent risk factors for DR were longer duration of diabetes (odds ratio [OR] 3.07, 95% confidence interval [CI] 1.94, 4.85, per 5 years of duration), higher FPG levels (OR 1.17; 95% CI: 1.08, 1.27, per mmol/l increase) and higher systolic blood pressure (OR 1.22; 95% CI: 1.08, 1.37, per 10 mmHg increase). For newly diagnosed diabetes, the only significant factor of DR was higher FPG levels (OR 1.17; 95% CI: 1.05, 1.29, per mmol/l increase). Conclusions: In rural Chinese persons with diabetes, longer diabetes duration, hyperglycaemia and elevated blood pressure are risk factors for DR. These findings under-score the importance of controlling classic risk factors for DR in developing countries, where diabetes prevalence is increasing.