Incidence and progression of diabetic retinopathy in Hong Kong Chinese with type 2 diabetes mellitus

Abstract

Objective We conducted a cohort study to determine the incidence and progression of diabetic retinopathy (DR) in a Chinese population with type 2 diabetes mellitus in a district hospital in Hong Kong, and to identify the risk factors associated with the development and progression of DR over 4 years. Research Design and Methods A total of 413 type 2 diabetic patients who followed up in our diabetic clinic and had a diabetic complication screening performed in 2001 were studied. The final analysis included 354 subjects (85.7%) after a mean follow-up period of 4.2 years. The severity of DR was graded according to the modified Early Treatment Diabetic Retinopathy Study (ETDRS). The relationship between clinical variables and DR development and progression was determined. Results The baseline prevalence of DR was 39.2%. On 4-year follow-up, the incidence of DR was 20.3% (43 of 212). In those with baseline DR, 34.7% (42 of 121) progressed by ≥2 steps in ETDRS. On multivariate analysis, a high baseline glycosylated hemoglobin (HbA 1c) was the only predictor of DR development, while macroalbuminuria and high mean HbA 1c predicted progression. Regression of DR, defined by a ≥2-step decrement in ETDRS, occurred in 13.2% (12 of 91) of subjects and was associated with lower baseline HbA 1c and absence of albuminuria. Conclusion The incidence of DR in our study was similar to—but progression of DR was higher than—those reported in Caucasians. More frequent retinal screening should be offered to those with baseline DR, high HbA 1c, or albuminuria. Good glycemic control is important in order to prevent the development and progression of DR, and can lead to regression of DR.