Gastroenterology
Sonya Collins
GLP-1 receptor agonists like semaglutide (Ozempic) have transformed the management of T2D and obesity. However, their increasing use has introduced new challenges in other areas of clinical care, including GI procedures. Delayed gastric emptying, a known effect of these agents, can lead to food retention or incomplete bowel clearing and result in incomplete procedures or complications. As the prevalence of GLP-1 therapy rises, adapting guidelines and counseling for patients prior to endoscopy and colonoscopy is crucial.
Pharmacists need to be aware of how GLP-1 drugs may complicate colonoscopy and endoscopy as two recent studies describe.
GLP-s may impede colonoscopy
Patients who take GLP-1s are more likely to have inadequate bowel prep prior to colonoscopy, according to a review by Beran and colleagues published online on February 12, 2025, in The American Journal of Gastroenterology.
The authors analyzed the results of five studies that included 10,833 patients, more than half of whom were taking GLP-1s. Compared to controls, those taking GLP-1s were twice as likely to have inadequate bowel prep and their Boston bowel preparation scale scores were lower.
While there are no national guidelines calling for patients to hold GLP-1s during bowel prep, many individual medical practices and health systems, such as Veterans Affairs, instruct patients to hold these medications for up to a week prior to a colonoscopy.
“One option would be to hold the drug prior to bowel prep,” said Beran, who is a GI fellow at Indiana University School of Medicine. “But we don’t know how long the half-life of this drug is, so the solution may be to do an extended bowel prep.”
For patients on GLP-1s preparing for a colonoscopy, pharmacists might review with patients their physician’s instructions regarding holding medication or extending bowel preparation prior to the procedure.
GLP-1s less risky in upper endoscopy than previously believed
Previous warnings regarding risk of food retention on upper endoscopy for people who take GLP-1s may have been overestimated, according to a multicenter cross-sectional study by Jennifer Phan, MD, and colleagues published in March 2025 in The American Journal of Gastroenterology.
The study included 815 patients on GLP-1s. Among them, 8.7% had retained gastric contents on endoscopy, 93% of whom had T2D. Only one patient required unplanned intubation, and none experienced an aspiration event. Those whose GLP-1 medication was held based on guidance from the American Society of Anesthesiologists were less likely to have retained gastric contents, but there was not a significant difference in intubation or aborting procedure rates. A1C correlated positively with odds of food retention. Every 1% increase in A1C was associated with a 36% increase in risk of retention.
“The risk of food retention has been a little bit overblown,” said Phan, who is medical director of the Hoag Advanced Endoscopy Center and Director of Bariatric Endoscopy at the Hoag Digestive Health Institute in Orange County, CA. “It’s not a matter of holding the medication for a week. It’s a matter of the patient’s comorbidities. In patients who are brutally diabetic, on high levels of insulin or multiple medications, you would consider holding the last injection dose for a week.”
Further studies have shown that patients taking GLP-1s for obesity, rather than diabetes, face less risk, Phan said. “Holding is not necessary for these patients,” Phan said. “A clear liquid diet for 24 to 48 hours may be sufficient for the vast majority of these patients who are on GLP-1s.”
Recommendations are in flux
Pharmacists may want to pay attention to ongoing research on this topic. The results of these studies are based only on currently available GLP-1s.
“As we start to see combination medications, such as anti-amylin receptors,” Phan said, “this ethos may not apply. We may need to reevaluate once more of those are on the market.” ■