Corneal endothelium and central corneal thickness changes in type 2 diabetes mellitus

PURPOSE This study was conducted to compare the corneal endothelial cell density (ECD), morphological features, and central corneal thickness (CCT) in type 2 diabetes mellitus (DM) with age-matched, nondiabetic control subjects using EM-3000 Specular Microscope. STUDY DESIGN This was a prospective, hospital-based, nonrandomized, case-control, observational, and quantitative study. SUBJECTS AND METHODS The study included 57 patients (57 eyes) with type 2 DM and 45 control (nondiabetic) subjects (45 eyes). The corneal endothelial structure and CCT were examined in all eyes by noncontact specular microscopy using EM-3000 Specular Microscope. The endothelial structure was studied for ECD, coefficient of variation of cell area (CV), and percentage of hexagonal cells. RESULTS The study included 36 eyes without diabetic retinopathy (DR), 14 eyes with nonproliferative DR, and 7 eyes with proliferative DR. There were 26 eyes with a duration of ≤10 years and 31 eyes with a duration of >10 years. Also, there were 24 eyes with HbA1c ≤7.5% and 33 eyes with HbA1c >7.5%. ECD was significantly lower in the diabetic cornea than in control group (P=0.014). CV was higher in diabetic cornea (P=0.008). The diabetic cornea group had lower percentage of hexagonal cells than the control group, but the difference was not statistically significant (P=0.603). Also, diabetic cornea was thicker than control group, but not statistically significant (P=0.301). CONCLUSION This study documented that type 2 DM causes a significant reduction of ECD and increased CV (polymegathism). Also, diabetic cornea has increased CCT and lower percentage of hexagonal cells than normal subjects, but without statistical significance.