Diabetic retinopathy is not present in newly diagnosed diabetic patients

Abstract

To the Editor: Ponto and colleagues would have us believe that 12.6% of type 2 diabetic patients newly diagnosed through a screening programme of the general population had retinopathy at the time of diagnosis [1]. This is not the case. They used fundus photographs that were interpreted using the criteria of the Early Treatment Diabetic Retinopathy Study (ETDRS). Those criteria for mild diabetic retinopathy are 'at least one microaneurysm, and definition not met for moderate nonproliferative retinopathy, severe nonproliferative retinopathy, early proliferative retinopathy, or high-risk proliferative retinopathy' [2]. Of the patients who screened positive for diabetes, 11.6% had mild diabetic retinopathy by these criteria [1]. It turns out that 5-10% of the general population without diabetes or hypertension have signs of isolated retinopathy that meet the ETDRS criteria for 'mild' diabetic retinopathy. Furthermore, up to 10% of people over the age of 40 years without both diabetes and isolated retinopathy signs develop these isolated retinopathy signs over 5 years, while remaining free of diabetes [3]. Indeed, Ponto and colleagues also found that 10% of age-and sex-matched controls without diabetes had changes that fulfilled the ETDRS criteria for mild diabetic retinopathy [4]. As a result of the issue of signs of isolated retinopathy in the general population, the cut-off point for HbA 1c levels for the diagnosis of diabetes was based on the presence of moderate diabetic retinopathy, not mild diabetic retinopathy [5]. Thus, the concept that prolonged hyperglycaemia (somehow) causes diabetic retinopathy remains intact, allowing our patients and their carers the opportunity to forestall this complication [6].