Objective: To determine the prevalence and factors associated with Diabetic Retinopathy (DR) of type 1 diabetes mellitus in Thailand.
Material and Method: A cross-sectional, multicenter, hospital-based study was carried out from April to December 2003. Diabetic patients in diabetic clinics of 11 tertiary centers were registered. Retinopathy was evaluated by the ophthalmologists.
Results: Seven thousand one hundred and nineteen diabetic patients received retinal examination. The number of patients with type 1 diabetes was 347. The prevalence of DR in type 1 diabetes was 21.6% (75). This consisted of Non-Proliferative DR (NPDR) 10.9% (38) and Proliferative DR (PDR) 10.7%. Patients with DR were significantly older, predominantly female, longer duration of diabetes, had higher BMI, systolic Blood Pressure (BP), diastolic BP, serum creatinine, and TriGlycerides (TG) levels than those without DR. Both groups of patients were not different in term of plasma glucose and glycosylated hemoglobin levels. Although the patients with DR had a higher percentage of overt proteinuria than those without DR, there was no difference in percentage of patients with positive microalbuminuria in both groups. This may be explained by limitation of data (only 16% had results of microalbuminuria and 19% had results of proteinuria). After adjusted for duration of diabetes, serum creatinine and smoking status, factors (adjusted odds ratio [95% confidence interval]) associated with DR were duration of diabetes 5-9.9 years (4.0 [1.49-10.91]), 10-14.9 years (6.86 [2.45-19.20]), 15-19.9 years (21.13 [7.22-61.78]), ≥ 20 years (22.15 [7.32-66.99]) when compared with duration of diabetes less than 5 years, serum creatinine > 2 mg/dl (6.0 [2.09-17.22]) when compared with creatinine less than 2 mg/dl. From the presented model, age, gender, systolic BP > 140 mmHg, diastolic BP > 90 mmHg, serum TG and smoking status were not factors associated with DR.
Conclusion: Diabetic retinopathy affects about one fifth of type 1 diabetic patients in our study. The authors found the factors associated with DR in type 1 DM were duration of diabetes and serum creatinine. Regular screening for DR and more aggressive management of metabolic factors should be done to reduce the prevalence of DR.

Keywords: Type 1 diabetes, Diabetic retinopathy