Objective: To compare the corneal endothelial structure including endothelial cell density, polymorphism, and pleomorphism, in diabetic and non-diabetic subjects.

Material and Method: The corneal endothelial structure of diabetic and non-diabetic subjects were measured by specular microscope (Confoscan4 (CS4), Nidek) for endothelial cell density, percentage of polymegathism, and percentage of hexagonal cells. The data were analyzed using the descriptive statistics and the unpaired t-test.

Results: There were 171 eyes of 90 diabetic patients with the mean age of 58.49±9.78 years, and 156 eyes of 90 non-diabetic subjects with the mean age of 58.98±13.12 years. Three parameters of measurement revealed no significant difference (p>0.05). The over one year diabetic patients, however, demonstrated a decreased percentage of hexagonal cells statistically significant (p<0.05), while the over two years diabetic patients demonstrated a decreased percentage of hexagonal cell and an increased percentage of polymegathism statistically significant (p<0.05).

Conclusion: The corneal endothelial structure is not different between diabetic and non-diabetic groups. When the disease progresses, however, the hexagonal cells decrease at first, followed by the polymegathism. No difference shows in endothelial cell density.

Keywords: Corneal endothelium, Diabetes, Specular microscope, Polymorphism, Pleomorphism