Background: The corneal endothelial structure was abnormal in diabetic patients, but there were many factors affecting them.
Objective: To compare the corneal endothelial structure including endothelial cell density, hexagonality and polymegathism percentage, in diabetic related to diabetic duration and non-diabetic subjects.
Material and Method: The corneal endothelial structure of diabetic related to diabetic duration and non-diabetic subjects were examined by specular microscope (Confoscan4 CS4, Nidek) included endothelial cell density, hexagonality and polymegathism percentage. The data were analyzed using the descriptive statistics and the unpaired t-test.
Results: There were 271 eyes of 148 diabetic patients with the mean age of 61.04+9.51 years, and 82 eyes of 46 non-diabetic subjects with the mean age of 57.93+11.30 years. The diabetic patients were divided into 3 groups based on diabetic duration (<5 years, 5-10 years, and >10 years). All groups of diabetic endothelial cell density were less than non-diabetic group with statistical significance (p<0.05). In all groups of diabetic, the polymegathism percentage was more than while the hexagonality percentage was less than non-diabetic group with statistical insignificance (p>0.05). All endothelial parameters insignificantly differed between 3 groups of diabetic (p>0.05).
Conclusion: The diabetic corneal endothelial structure was abnormal, especially decreased cell density, compared to the non-diabetic subjects. The abnormalities and diabetic duration were unrelated.

Keywords: Corneal endothelium, Diabetes, Specular microscope, Polymegathism, Hexagonal cell