Background: It is likely that improved treatment of diabetes during the last decades has led to a declining prevalence of retinopathy. We have assessed whether this is the case for patients with type I diabetes.
Material and methods: Medical records were retrospectively reviewed for all patients who were diagnosed with type 1 diabetes in the periods 1960-1975 (early group) and 1985-1990 (late group) at the diabetes clinic in St. Olavs Hospital (Trondheim). Information on the prevalence of retinopathy ten and 15 years after diabetes onset was obtained from hospital records and private ophthalmologists in Trondheim.
Results: 125 patients were identified in the early group and 147 patients in the late group. The prevalence of proliferative retinopathy was higher in the early group than in the late group, both after ten years (4% vs. 0%, p = 0.04) and 15 years (13% vs. 5%, p = 0.04) of diabetes. The prevalence of background retinopathy was not significantly different between the two groups after ten (12% vs. 14%, p = 0.70) or 15 years (29% vs. 24%, p = 0.36) of diabetes.
Interpretation: Our results indicate that the prevalence of proliferative retinopathy is decreasing in patients with type 1 diabetes in Norway. Explanations may be improved follow-up and treatment of diabetes and diabetic retinopathy.