Background: Diabetes mellitus, or DM, is a condition that increases the risk of developing cataracts. Cataracts are one of the leading causes of blindness; some studies report that DM patients with cataracts have an increased risk of progression, while other studies report that their progression is merely the natural course of the disease. 
Objectives: To estimate incidence of macular edema (ME), in patients with and without diabetes following phacoemulsification operation.
Patients and methods: This study is a prospective cross- sectional observational which enrolled 100 eyes of one hundred subjects, fifty  patients suffering diabetes (group 1) and fifty patients suffer no diabetes (group 2) having immature senile cataract . Participants belonged to the ophthalmology department of South Valley   University. OCT was done preoperatively and postoperatively by one month.
Results:  Mean age of patients with and without diabetes was 66.48 and 66.16 respectively. Males represent 64% of group 1 and , and 80% of group 2 respectively. Both groups showed a considerable rise in the central macular thickness one month postoperatively, but there was no potential variation statistically in central macular thickness between the two groups neither before, nor after the surgery.   
Conclusion:    There is an increase in central macular thickness as a result of the effects of phacoemulsification on the macula in patients with and without diabetes. OCT is the single most crucial diagnostic and prognostic tool for managing macular oedema. But long-term studies are needed to prove longer effect of uncomplicated phacoemulsification and macular thickness and its visual impact.