The corneal endothelium and thickness in type II diabetes mellitus.

PURPOSE To compare the endothelial structure and thickness of the cornea in diabetic and nondiabetic patients, and to evaluate the systemic and ocular factors that contribute to the damage of endothelial cells in diabetic patients. METHODS The corneal endothelial structure and central corneal thickness (CCT) were investigated in 99 type II diabetic patients (99 eyes) and in 97 nondiabetic patients (97 eyes). The endothelial structure was examined for cell density, coefficient of variation of cell area, and percentage of hexagonal cells. The correlation between CCT and the grade of diabetic retinopathy was evaluated. Multivariate regression analysis was performed to assess systemic factors (patient age, sex, duration of diabetes mellitus, hemoglobin A(1c) value, glucose in urine, blood urea nitrogen value, and creatine value) and ocular factors (grade of diabetic retinopathy and history of photocoagulation) related to endothelial cell density. RESULTS The endothelial cell density was decreased and the coefficient of variation of cell area was increased in diabetic patients (P <.05). However, the percentage of hexagonal cells and CCT in diabetic patients was not significantly different from that in nondiabetic patients. CCT was similar regardless of the stage of diabetic retinopathy. Multivariate regression analysis indicated that none of the systemic or ocular factors was significantly correlated with the endothelial cell density. CONCLUSIONS Corneal endothelial cell structure was damaged, but CCT was not increased in type II diabetic patients. There were no systemic or ocular factors at any one point to induce corneal endothelial damage.