Patients and Methods: The study included 40 eyes of 40 patients scheduled for cataract surgeryby phacoemulsification at Al-Azhar University Hospitals. The patients were assigned to 2 groups. Group 1: Twenty patients without diabetes were used as a control group. Group 2: Twenty patients diagnosed with diabetes based on medical history and all were on medical treatment. In this prospective randomized study, preoperative specular microscopy and serial postoperative specular microscopy (Topcon SP- 1P, Topcon Medical Inc., Japa) were performed to evaluate endothelial cell count changes over 6 months. The main outcome measures were central corneal thickness (CCT), cell density (CD), coefficient of variation (CV), hexagonality (HEX) and best corrected visual acuity (BCVA). Results: In term of CCT, BCVA, HEX and CD, the differences between preoperative and postoperative values are statistically significant in both groups. On the other hand, in term of CV, the difference between preoperative and postoperative CV is statistically insignificant in both groups. Conclusion: The endothelium in diabetic subjects is more vulnerable to surgical traumaand has a lower capability in the process of repair.