Changing trends in the prevalence of diabetic retinopathy in type 1 diabetes mellitus from 1990 to 2018: A retrospective study in a Portuguese population

Abstract

PurposeTo estimate the prevalence of diabetic retinopathy /(DR) in a Portuguese population with type 1 diabetes (T1DM). MethodsRetrospective review of all patients with T1DM, whose reference center was Centro Hospitalar de São João, a tertiary center in Portugal, who were diagnosed between 1990 and 2018. DR was classified based on fundus examination in medical records as (0) no evidence of retinopathy, (1) mild non-proliferative retinopathy (NPDR); (2) moderate to severe non-proliferative retinopathy (NPDR) and (3) proliferative retinopathy (PDR). Patients were classified according to the eye with a worse retinopathy stage. Follow-up was considered as time between the diagnosis of diabetes and the last funduscopic evaluation. Results233 patients met the inclusion and exclusion criteria. The prevalence of any DR at less than 5, 10, 15, 20 and more than 20-years of DM was 1.8%, 10.4%, 34.8%, 54.1% and 71.2% respectively. The overall prevalence of DR was 43.3% (n = 101). At the last observation, 43 patients (18.5%) had mild NPDR, 34 patients (14.6%) had moderate to severe NPDR and 24 patients (10.3%) had PDR. The longer the disease duration, the higher the number of patients with DR. ConclusionThe prevalence of DR in our cohort was 34.8% after 15 years of systemic disease and 54.1% after 20 years, which is lower than what has been reported in the literature. Further multicentric prospective studies, are needed to clarify changes in the epidemiology of DR in type 1 diabetics.