Background: Inflammatory bowel disease (IBD) is a term that refers to a category of idiopathic chronic inflammatory bowel diseases. There are a number of theories that link microbial infections to IBD. One of the opportunistic viral infections linked to this disease is cytomegalovirus.

Aim of the Work: to evaluate the role of CMV infection in diabetic patients with ulcerative colitis especially after failure of medical treatment.

Material and Methods: This study carried out on 185 patients, attending and admitted in the Theodore Bilharz Research Institute at the clinic and the department of gastroenterology from January, 2019 till January, 2021. At the end of the 1st year of coloscopic follow up , coloscopic biopsies were taken from all patients for detection of CMV associated colonic infection using Polymerase chain reaction (PCR).

Results: The results of the study showed that, CMV PCR was positive in seven patients in the diabetic group and two patients in the non-diabetic group.
Conclusion: A positive association between UC and CMV was noticed but still needing further studies for detection of the pathogenesis on a large scale.