The effects of type 2 diabetes mellitus on the corneal endothelium and central corneal thickness

Aim of this study is to evaluate the differences in corneal endothelial cell morphology and corneal thickness in patients with and without type 2 diabetes related to age, disease duration, and HbA1c percentage. This retrospective cross-sectional study included 511 (1022 eyes) type 2 diabetes patients and 900 (1799 eyes) non-diabetic patients. The endothelial cell density (ECD), variation in endothelial cell size (CV), percentage of hexagonal cells, and central corneal thickness (CCT) were analyzed using a noncontact specular microscope and a Pentacam Scheimpflug camera. We also examined the correlation between the corneal parameters and the duration of diabetes. For total ages, the subjects with type 2 diabetes showed significantly lower ECD, hexagonality, higher CV, and thicker CCT than the control group. This difference was more pronounced in patients with long-standing DM (≥ 10 years) and high HbA1c (≥ 7%). When stratified by age group, from the 60 s group, corneal endothelial cell parameters showed a statistically significant difference between DM and control groups. The duration of diabetes was inversely correlated with ECD (r = − 0.167; p = 0.000). These findings suggest that diabetes affects corneal endothelial cell in older age and those with long-standing DM and higher HbA1c. Regular corneal endothelial examinations are required in diabetic patients.