Acute ischaemic colitis after initiation of tirzepatide in an elderly patient with type 2 diabetes

Tirzepatide, a dual GLP-1/GIP receptor agonist, is increasingly used for the treatment of type 2 diabetes and obesity. While gastrointestinal side effects such as nausea and diarrhoea are common, reports of ischemic colitis potentially associated with tirzepatide are extremely rare. Understanding potential mechanisms is critical for early recognition and management. We report the case of a 77-year-old woman with type 2 diabetes, severe obesity, and cardiovascular comorbidities, who developed acute onset abdominal pain and rectal bleeding two days after her second dose of tirzepatide. On admission, laboratory evaluation showed leucocytosis and elevated C-reactive protein. Abdominal CT demonstrated segmental left-sided colitis with diverticulosis. Rectosigmoidoscopy revealed hyperaemic, oedematous, friable mucosa with superficial ulcerations in the sigmoid colon. Histology was consistent with erosive colitis with features suggestive of ischemic injury. Infectious workup was negative. The patient was promptly started on intravenous metronidazole, fluid resuscitation, and pantoprazole. Clinical symptoms resolved over the subsequent days, and laboratory markers improved. This case highlights a potential association between tirzepatide therapy and ischemic colitis. Mechanisms may include delayed gastrointestinal motility, increased intraluminal pressure, relative hypovolemia, and possible neuroenteric microvascular modulation. Clinicians should be aware of this rare but serious complication, particularly in patients with cardiovascular comorbidities.