Diabetic retinopathy, visual acuity, and medical risk indicators - A continuous 10-year follow-up study in Type 1 diabetic patients under routine care

The objective of this study was to describe incidence and progression of di abetic retinopathy in relation to medical risk indicators as well as visual acuity outcome after a continuous follow-up period of 10 years in a Type I diabetic population treated under routine care. The incidence and progress ion of retinopathy and their association to HbA(1c), blood pressure, urinar y albumin, serum creatinine levels, and insulin dosage were studied prospec tively in 452 Type I diabetic patients. The degree of retinopathy was class ified as no retinopathy, background, or sight-threatening retinopathy, i.e. clinically significant macular edema, severe nonproliferative, or prolifer ative retinopathy. Impaired visual acuity was defined as a visual acuity < 0.5 and blindness as a visual acuity less than or equal to 0.1 in the best eye. In patients still alive at follow-up (n = 344), 61% (69/114) developed any retinopathy, 45% (51/114) background retinopathy, and 16% (18/114) sig ht-threatening retinopathy. Progression from background to sight-threatenin g retinopathy occurred in 56% (73/131). In 2% (6/335), visual acuity droppe d to < 0.5 and in less than 1% (3/340) to less than or equal to 0.1. Patien ts who developed any retinopathy and patients who progressed to sight-threa tening retinopathy had higher mean HbA(1c) levels over time compared to tho se who remained stable (P < .001 in both cases). Patients who developed any retinopathy had higher levels of mean diastolic blood pressure (P = .036), whereas no differences were seen in systolic blood pressure levels between the groups. Cox regression analysis, including all patients, showed mean H bA(1c) to be an independent risk indicator for both development and progres sion of retinopathy, whereas mean diastolic blood pressure was only a risk indicator for the incidence of retinopathy. Metabolic control is an importa nt risk indicator for both development and progression of retinopathy, wher eas diastolic blood pressure is important for the development of retinopath y in Type I diabetes. The number of patients who became blind during 10 yea rs of follow-up was low. (C) 2001 Elsevier Science Inc. All rights reserved .