Prevalence of and risk factors for diabetic retinopathy in Koreans with type II diabetes: baseline characteristics of Seoul Metropolitan City-Diabetes Prevention Program (SMC-DPP) participants

Objective To evaluate the prevalence of and risk factors for diabetic retinopathy (DR) in Koreans with type II diabetes. Methods Subjects (400 male, 296 female) aged 30-65 years (mean 55.3 years) with hyperglycaemia (fasting plasma glucose >= 7.0 mmol/ml) or known diabetes (mean+/-SD duration 6.36+/-5.73 years) were enrolled in the Seoul Metro-City Diabetes Prevention Program (SMC-DPP) from September 2008 to September 2009. The severity of DR was diagnosed by grading fundus photographs taken from five standard fields per eye and categorised following the Early Treatment of Diabetic Retinopathy Study grading protocol. All participants underwent routine clinical and laboratory examinations to evaluate risk factors for DR. Results The overall prevalence of any type of DR was 18.7%. Logistic regression analyses showed that the following factors were significantly associated with DR after adjustment for age and gender, duration of diabetes, serum glycated haemoglobin A1c (HbA1c), mean arterial pressure, serum total cholesterol and serum triglycerides: duration of diabetes (OR 1.14, 95% CI 1.10 to 1.18, for 1 year increase), HbA1c (OR 1.49, 95% CI 1.20 to 1.85, for 1% increase), serum concentration of insulin (OR 0.87, 95% CI 0.81 to 0.94, for 1 mu IU/ml increase), homoeostasis model assessment of insulin resistance (OR 0.06, 95% CI 0.01 to 0.29, for 10 unit increase), and presence of macroalbuminuria (OR 5.14, 95% CI 1.45 to 18.20, albumin to creatinine ratio >300 mg/g). Conclusions In addition to traditional risk factors, insulin resistance was associated with an increased risk of DR in Koreans with type 2 diabetes.