The rapid adoption of glucagon-like peptide 1 receptor agonists (GLP-1 RAs) for the treatment of diabetes and weight loss has led to a corresponding interest in their potential side effects. Several recent studies have sought to expound upon what role, if any, GLP-1 RAs may have in increasing the risk for specific gastrointestinal (GI) adverse events.
Herein is a summary of the most current information on this topic, as well as my best guidance for clinicians on integrating it into the clinical care of their patients.
Aspiration Risks
Albiglutide, dulaglutide, exenatide, liraglutide, lixisenatide, semaglutide, and tirzepatide are among the class of medications known as GLP-1 RAs. These medications all work by mimicking the action of hormonal incretins, which are released postprandially. Incretins affect the pancreatic glucose-dependent release of insulin, inhibit release of glucagon, stimulate satiety, and reduce gastric emptying. This last effect has raised concerns that patients taking GLP-1 RAs might be at an elevated risk for endoscopy-related aspiration.
In June 2023, the American Society of Anesthesiologists released recommendations asking providers to consider holding back GLP-1 RAs in patients with scheduled elective procedures.
In August 2023, five national GI societies — the American Gastroenterological Association, American Association for the Study of Liver Diseases, American College of Gastroenterology, American Society for Gastrointestinal Endoscopy, and North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition — issued their own joint statement on the issue.
In the absence of sufficient evidence, these groups suggested that healthcare providers "exercise best practices when performing endoscopy on these patients on GLP-1 [RAs]." They called for more data and encouraged key stakeholders to work together to develop the necessary evidence to provide guidance for these patients prior to elective endoscopy. A rapid clinical update issued by the American Gastroenterological Association in 2024 was consistent with these earlier multisociety recommendations.
Two studies presented at this year's Digestive Disease Week provided additional reassurance that concerns about aspiration with these medications were perhaps unwarranted.
The first (since published in The American Journal of Gastroenterology) was a case-control study of 16,295 patients undergoing upper endoscopy, among whom 306 were taking GLP-1 RAs. It showed a higher rate of solid gastric residue among those taking GLP-1 RAs compared with controls (14% vs 4%, respectively). Patients who had prolonged fasting and clear liquids for concurrent colonoscopy had lower residue rates (2% vs 11%, respectively). However, there were no recorded incidents of procedural complications or aspiration.
The second was a retrospective cohort study using TriNetX, a federated cloud-based network pulling millions of data points from multiple US healthcare organizations. It found that the incidence of aspiration pneumonitis and emergent intubation during or immediately after esophagogastroduodenoscopy and colonoscopy among those taking GLP-1 RAs was not increased compared with those not taking these medications.
These were followed in June 2024 by a systematic review and meta-analysis published by Hiramoto and colleagues, which included 15 studies. The researchers showed a 36-minute prolongation for solid-food emptying and no delay in liquid emptying for patients taking GLP-1 RAs vs controls. The authors concluded that the minimal delay in solid-food emptying would be offset by standard preprocedural fasting periods.
There is concern that patients with complicated type 2 diabetes may have a bit more of a risk for aspiration. However, this was not supported by an analysis from Barlowe and colleagues, who used a national claims database to identify 15,119 patients with type 2 diabetes on GLP-1 RAs. They found no increased events of pulmonary complications (ie, aspiration, pneumonia, respiratory failure) within 14 days following esophagogastroduodenoscopy. Additional evidence suggests that the risk for aspiration in these patients seems to be offset by prolonged fasting and intake of clear liquids.
Although physicians clearly need to use clinical judgement when performing endoscopic procedures on these patients, the emerging evidence on safety has been encouraging.
Association With GI Adverse Events
A recent retrospective analysis of real-world data from 10,328 new users of GLP-1 RAs with diabetes/obesity reported that the most common GI adverse events in this cohort were abdominal pain (57.6%), constipation (30.4%), diarrhea (32.7%), nausea and vomiting (23.4%), GI bleeding (15.9%), gastroparesis (5.1%), and pancreatitis (3.4%).
Notably, dulaglutide and liraglutide had higher rates of abdominal pain, constipation, diarrhea, and nausea and vomiting than did semaglutide and exenatide. Compared with semaglutide, dulaglutide and liraglutide had slightly higher odds of abdominal pain, gastroparesis, and nausea and vomiting. There were no significant differences between the GLP-1 RAs in the risk for GI bleeding or pancreatitis.
A 2023 report in JAMA observed that the risk for bowel obstruction is also elevated among patients using these agents for weight loss. Possible reasons for this are currently unknown.
Studies are needed to analyze possible variations in safety profiles between GLP-1 RAs to better guide selection of these drugs, particularly in patients with GI risk factors. Furthermore, the causal relationship between GLP-1 RAs with other concomitant medications requires further investigation.
Although relatively infrequent, the risk for GI adverse events should be given special consideration by providers when prescribing them for weight loss, because the risk/benefit ratios may be different from those in patients with diabetes.
A Lack of Hepatic Concerns
GLP-1 RAs have demonstrated a significant impact on body weight and glycemic control, as well as beneficial effects on clinical, biochemical, and histologic markers in patients with metabolic dysfunction–associated steatotic liver disease (MASLD). These favorable changes are evident by reductions in the hepatic cytolysis markers (ie, aspartate aminotransferase and alanine aminotransferase).
GLP-1 RAs may provide a protective function by reducing the accumulation of hepatic triglycerides and expression of several collagen genes. Some preclinical data suggest a risk reduction for progression to hepatocellular carcinoma, and animal studies indicate that complete suppression of hepatic carcinogenesis is achieved with liraglutide.
The most recent assessment of risk reduction for MASLD progression comes from a Scandinavian cohort analysis of national registries. In looking at 91,479 patients using GLP-1 RAs, investigators demonstrated this treatment was associated with a significant reduction in the composite primary endpoint of hepatocellular carcinoma, as well as both compensated and decompensated cirrhosis.
Given the various favorable hepatic effects of GLP-1 RAs, it is likely that the composite benefit on MASLD is multifactorial. The current literature is clear that it is safe to use these agents across the spectrum of MASLD with or without fibrosis, although it must be noted that GLP-1 RAs are not approved by the US Food and Drug Administration for this indication.
David A. Johnson, MD, a regular contributor to Medscape, is professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia, and a past president of the American College of Gastroenterology. His primary focus is the clinical practice of gastroenterology. He has published extensively in the internal medicine/gastroenterology literature, with principal research interests in esophageal and colon disease, and more recently in sleep and microbiome effects on gastrointestinal health and disease.