Changes in corneal endothelial cell density and central corneal thickness in patients with type 2 diabetes mellitus

Background and objectives: The corneal endothelium is essential for maintaining corneal transparency and visual function. Chronic hyperglycaemia in type 2 diabetes mellitus (T2DM) can impair endothelial pump activity, resulting in reduced endothelial cell density (ECD) and increased central corneal thickness (CCT). Because endothelial cells do not regenerate, progressive cell loss may lead to irreversible endothelial decompensation. This study evaluates the association of T2DM with ECD and CCT and examines how these parameters relate to diabetes duration, glycaemic control (HbA1c) and diabetic retinopathy (DR). Materials and methods: This cross-sectional study, conducted at BIRDEM General Hospital, included 86 patients with T2DM and 86 individuals in the non-diabetic group. The T2DM group was subdivided by DR status (no DR, non-proliferative DR and proliferative DR). Following standard ophthalmic examinations, specular microscopy was performed to measure ECD and CCT in the right eye. Data were analyzed using t-test, ANOVA, correlation analysis and multivariate regression (SPSS version 26). Results: Individuals with T2DM demonstrated a significant loss of endothelial cells, with mean ECD 275 cells/mm² lower than the non-diabetic group (2585·18 ± 263·12 vs 2860·06 ± 244·45 cells/mm²; p