GLP-1 Users Should Fast 24 Hours Before Anesthesia

Medscape

05-06-2025

Patients taking the new class of weight-loss drugs do not need to stop these medications prior to procedures requiring anesthesia, but they should adhere to longer preoperative fasting times, according to a new multidisciplinary consensus statement.
The statement, led by the Society for Perioperative Assessment and Quality Improvement, recommends patients without significant gastrointestinal symptoms associated with glucagon-like peptide 1 receptor agonists (GLP-1 RAs) should fast from solid foods for 24 hours and stick to clear liquids prior to a procedure requiring anesthesia. This extended fasting time can help mitigate aspiration risk in these patients with delayed gastric emptying while retaining the benefits of continuing GLP-1 RAs, such as improved glycemic control.
The statement is 'the first to provide recommendations for perioperative management of patients taking GLP-1 RAs based on an in-depth systematic literature review of both clinical perioperative studies and gastric emptying data,' Adriana Oprea, MD, the first author of the document, and her colleagues wrote.
Changing Guidance
In June 2023, the American Society of Anesthesiologists (ASA) released the first guidance statement regarding preoperative management of patients on GLP-1 RAs, after some case reports documented aspiration events in these patients.
While the number of these events is generally low and rates of aspiration appear to be similar between patients on GLP-1 RAs and the general population, 'people got really worried with these drugs because of [the] delayed gastric emptying,' Oprea, an associate professor of anesthesiology at Yale School of Medicine in New Haven, Connecticut, told Medscape Medical News .
The 2023 ASA guidance recommended holding GLP-1 RAs for one half-life — a week for patients on long-acting medication and a day for short-acting GLP-1s. Due to a lack of adequate evidence at the time, the document suggested these patients should follow the standard ASA fasting guidelines of 8 hours after a full meal.
However, evidence suggests stopping GLP-1s for one half-life is not enough for the effects on gastric emptying to subside, according to the new statement. For longer-acting drugs like dulaglutide, semaglutide, and tirzepatide, patients would need to discontinue these medications for several weeks to restore normal gastrointestinal motility.
For patients with type 2 diabetes, discontinuation of these medications over this period could lead to poor glycemic control, which is linked to worse postoperative outcomes. For patients taking GLP-1 RAs for weight loss, restarting these medications can result in increased gastrointestinal symptoms, Oprea said, such as nausea, vomiting, diarrhea, or constipation.
'Because adverse effects are more prevalent at higher GLP-1 RA doses, discontinuation of these medications might lead to a high likelihood of side effects upon medication reinitiation or require reinitiation of therapy at lower doses followed by dose reescalation,' Oprea's group wrote. 'This is logistically difficult for both patients and treating clinicians.'
In October 2024, the ASA, along with other professional societies, published updated practice guidance stating GLP-1 RAs may be continued preoperatively in patients without an elevated risk for delayed gastric emptying and aspiration. Those defined as 'higher risk' included patients in the escalation phase, on weekly dosing, on higher doses, and with gastrointestinal symptoms.
The guidance advised these patients at higher risk for delayed stomach emptying can help mitigate aspiration risk by following a 24-hour liquid diet.
This updated guidance also received some criticism.
'As of yet, no studies have reported a difference in the incidence of increased residual gastric content that would justify treating patients differently on the basis of dose regimen and/or treatment phase,' wrote Glenio B. Mizubuti, MD, PhD, of the Kingston General Hospital, in Kingston, Ontario, Canada, and his colleagues in a letter to Anesthesiology . 'Similarly, the absence of ongoing digestive symptoms, while somewhat reassuring, should not be taken as a definitive sign of an empty stomach in GLP-1 RA users,' they wrote.
Continue Meds, Extend Fasting Times
This new consensus statement, published last month in the British Journal of Anaesthesia , recommends patients doing well on GLP-1 RAs should continue these medications preoperatively and follow a clear liquid diet for 24 hours before procedures requiring anesthesia.
The recommendations were based on a systematic review of 112 studies and a modified Delphi process and were co-sponsored and endorsed by the American Association of Clinical Endocrinology.
'From our review of the literature, we feel that the fasting times are the most important factor that could decrease the risk of having residual gastric content in the stomach in a patient on GLP-1 RAs when they're scheduled to have a procedure that requires anesthesia,' Oprea said.
The consensus also recommends patients on GLP-1s fast from high-carbohydrate-content clear liquids (containing 10% or more glucose) for 8 hours before and stop drinking any liquids four hours before these procedures. Inpatient and outpatients can restart GLP-1 RAs when they resume their original diets.
Patients with significant gastrointestinal symptoms including severe nausea, vomiting, and inability to tolerate oral intake should postpone elective procedures that require anesthesia and refer to their prescribing physician for diet and medication modifications to manage symptoms, the authors advised.
'Our recommendation for a clear liquid diet for 24 hours preprocedurally might appear overly restrictive. However, evidence points to the safety of this approach in patients on GLP-1 RAs,' they wrote.