Glucagonlike peptide–1 receptor agonists (GLP-1 RAs), used for diabetes or obesity, are associated with a significantly lower quality of bowel preparation and a greater need for repeat colonoscopy, new research suggests.
“We began observing inadequate bowel preparation in our patients undergoing colonoscopy who were on GLP-1 RAs, which raised questions, especially given the association between these medications and delays in intestinal transit,” study investigator Eric. J. Vargas, MD, of the Mayo Clinic, Rochester, Minn., told this news organization. The team decided to investigate.
The “most surprising finding” was the “notably higher rate of inadequate bowel preparation, which necessitates a repeat colonoscopy within 12 months to ensure adequate screening and surveillance for colorectal cancers,” he said. “Specifically, for every 14 patients treated with GLP-1 RAs, one patient would require a repeat colonoscopy due to suboptimal preparation.”
In light of the findings, “clinicians should consider patients on GLP-1 RAs to be a population at risk for poor quality of bowel preparation,” he said.
The study was published online in the American Journal of Gastroenterology.
Low prep scores
The investigators analyzed a cohort of patients who underwent screening or surveillance colonoscopy at Mayo Clinic between 2021 and 2022. Patients taking any GLP-1 RA for diabetes or obesity at the time of colonoscopy were defined as “cases,” and those who were prescribed a GLP-1 RA at one point but had not taken it within 3 months of colonoscopy were controls.
The Boston Bowel Preparation Scale (BBPS) was used to assess bowel preparation quality.
The study included 446 patients: 265 (59%) taking a GLP-1 RA and 181 controls (41%). Overall, the average age was 59 years, about 54% were women, and 91% were White. Among those taking a GLP-1 RA, 86% had diabetes, as did 74% of controls.
Of patients on a GLP-1 RA, 48.8% took subcutaneous semaglutide, 3.1% took oral semaglutide, 34.6% took dulaglutide, 11% took liraglutide, and very small percentages took tirzepatide or exenatide.
There were no statistically significant differences between groups at baseline except for the diabetes diagnosis.
After diabetes was controlled for, the mean BBPS was significantly higher in controls than in GLP-1 RA recipients (7.5 vs. 7), and the percentage of patients with a total BBPS score less than 5 was significantly higher in the GLP-1 RA group than in the control group (15.5% vs. 6.6%).
In a secondary analysis of those with diabetes, the proportion of patients with a BBPS score less than or equal to 1 in any segment was higher in those taking a GLP-1 RA than in controls (24.9% vs. 13.3%).
The proportion of patients who required a repeat colonoscopy owing to inadequate bowel prep was higher among those taking a GLP-1 RA than among controls (18.9% vs. 11.1%). This corresponded to a number needed to harm of 14.
“GLP-1 RAs are increasingly used for the treatment of diabetes and obesity and have been demonstrated to reduce gastrointestinal motility,” the authors write. “Our data signal that the use of these medications in this patient population may be an additional factor in suboptimal bowel preparation.”
Limitations include the retrospective nature of the study, its focus on a single health system with a large majority of non-Hispanic White patients, and lack of data on diabetic complications and the use of insulin – all of which “necessitate caution in interpreting the findings,” the authors write.