Diabetic retinopathy II. The course of retinopathy in diabetics treated with oral hypoglycaemic agents and diet regime alone. A one year epidemiological cohort study of diabetes mellitus. The Island of Falster, Denmark.

The course of diabetic retinopathy was investigated in 273 out of 306 diabetics treated with oral hypoglycaemic agents (OHA) and 60 out of 72 diet-treated diabetics in an epidemiological cohort study in a period of one year. In the OHA-treated diabetics the allover prevalence of retinopathy did not change (P greater than 0.10) after one year (125/306 = 40.9% vs 122/273 = 44.7%). The one year incidence of new and deteriorated background was 3.7% and 6.6%, respectively. New cases of proliferative retinopathy developed in 1.1% and a worsening of pre-existing proliferative retinopathy in 1.8%. Among diabetics with pre-existing background retinopathy (n = 93) progressed, and 2% became proliferative. A worsening of retinopathy occurred more frequently (P less than 0.01) in diabetics with an onset age less than 60 years and with a duration greater than 5 years. The incidence of partial sight and legal blindness due to retinopathy was 2.2% and 1.9%, respectively, among all diabetics. Among diet-treated diabetics, 2 diabetics (3.3%) developed background retinopathy. None with pre-existing background retinopathy showed any deterioration.