Few classes of medications have changed the perioperative conversation as quickly as glucagon-like peptide-1 receptor agonists (GLP-1 RAs). Originally developed primarily for the management of type 2 diabetes, GLP-1 therapy is now widely used for obesity and metabolic disease.
For anesthesiologists, however, their growing use has introduced an important question: does a patient who has appropriately fasted before surgery truly have an empty stomach?
The concern stems from one of the therapeutic effects of GLP-1 receptor agonists: delayed gastric emptying. Although this contributes to satiety and weight loss, it also raises the possibility that solid gastric contents may remain despite conventional preoperative fasting. Under general anesthesia or deep sedation, regurgitation of gastric contents can lead to pulmonary aspiration, a rare but potentially life-threatening complication. Current literature supports an association between GLP-1 therapy and retained gastric contents, although the magnitude of the resulting aspiration risk remains less certain [1,5].
Although aspiration has received the most attention, perioperative management of GLP-1 therapy extends beyond the stomach. Clinicians must also consider glycemic control, dehydration, nutritional intake, nausea, vomiting, and the consequences of withholding treatment.
Guidance has evolved rapidly and continues to change
In 2023, early guidance from the American Society of Anesthesiologists (ASA) took a cautious approach. For elective procedures, patients taking a daily GLP-1 receptor agonist were advised to hold it on the day of surgery, while those taking a weekly preparation were advised to hold it for seven days. The recommendation was largely prompted by case reports and concern about delayed gastric emptying rather than robust prospective evidence [5].
The position subsequently changed.
In 2024, a U.S. multi-society group representing the ASA, American Gastroenterological Association, American Society for Metabolic and Bariatric Surgery and other organizations published updated clinical practice guidance. Rather than routinely withholding GLP-1 therapy, the guidance emphasizes individual assessment of aspiration risk, with many patients able to continue treatment before elective procedures [1].
This evolution illustrates an important principle in perioperative medicine: withholding a medication is not necessarily risk-free.
For patients using GLP-1 therapy for diabetes, interruption may worsen glycemic control. For patients receiving treatment for obesity, prolonged cessation can interfere with therapy and may create logistical or financial challenges when restarting treatment. There is also uncertainty about how long a long-acting medication would actually need to be withheld before its effect on gastric emptying meaningfully disappears.
Consequently, the question has shifted from “is this patient taking a GLP-1 drug?” to “what is this particular patient’s risk of delayed gastric emptying and aspiration?”
Who may be at higher risk?
The U.S. multi-society guidance identifies several circumstances that warrant additional consideration [1].
Patients may be at greater risk during the dose-escalation phase, when gastrointestinal effects are often more pronounced. Higher doses may also produce more gastrointestinal symptoms. Active nausea, vomiting, abdominal pain, dyspepsia or constipation should prompt additional assessment. Other disorders that independently slow gastric emptying may further increase risk.
For higher-risk patients, clinicians may consider measures such as a liquid-only diet for approximately 24 hours before the procedure, modification of the anesthetic plan to reduce aspiration risk, or point-of-care gastric ultrasound immediately before anesthesia when the necessary expertise is available. In selected circumstances, delaying an elective procedure may be appropriate [1].
Gastric ultrasound is particularly interesting for anesthesiologists because it can provide real-time information about whether the stomach appears empty, contains clear liquid, or contains solid material. It is not a replacement for clinical judgment, nor is expertise universally available, but it offers a potential method of moving from assumptions about gastric contents toward individualized assessment.
International guidance is converging, but is not identical
The broad trend toward continuing GLP-1 therapy is not limited to the United States.
In the United Kingdom, a 2025 multidisciplinary consensus statement involving the Association of Anaesthetists, Royal College of Anaesthetists, Centre for Perioperative Care and several diabetes, obesity and pharmacy organizations recommends that patients continue GLP-1 receptor agonists throughout the perioperative period. The UK guidance emphasizes individualized aspiration-risk assessment and mitigation strategies rather than routine medication cessation. It also notes that gastrointestinal symptoms alone should not be relied upon to determine gastric contents [2].
Depending on the situation, UK recommendations suggest consideration of regional anesthesia, gastric ultrasound, airway protection and other aspiration-risk mitigation strategies [2].
Australia and New Zealand have adopted an even more explicit dietary strategy. Updated 2025 recommendations endorsed by the Australian Diabetes Society, Australian and New Zealand College of Anaesthetists, Gastroenterological Society of Australia and other organizations recommend against elective cessation of GLP-1 and GLP-1/GIP therapies. However, they recommend a 24-hour clear-fluid diet followed by standard fasting for all patients receiving these medications before anesthesia or sedation [4].
If that dietary modification has not occurred, the Australian/New Zealand guidance recommends additional risk mitigation, potentially including gastric ultrasound, assessment of gastric contents, prokinetic therapy or alteration or deferral of the procedure [4].
Elsewhere in the Asia-Pacific region, including Singapore, no national anesthesia society has yet issued its own dedicated position statement on GLP-1 receptor agonists. In the absence of local guidance, clinicians in these settings generally draw on the U.S., UK or Australian/New Zealand frameworks and adapt them to institutional protocols, which underscores why an internationally consistent approach to risk assessment matters as much as the specific fasting rule adopted.
This is an important distinction. International recommendations increasingly agree that simply stopping GLP-1 therapy is not necessarily the solution, but there is not yet universal agreement regarding the optimal fasting strategy.
Why the evidence remains challenging
Much of the initial concern surrounding GLP-1 medications arose from case reports of retained gastric contents and pulmonary aspiration. Subsequent research has strengthened the association between GLP-1 therapy and residual gastric contents, but establishing the absolute increase in clinically significant aspiration events is considerably more difficult.
Pulmonary aspiration is uncommon to begin with. Randomized trials sufficiently large to detect differences in such a rare outcome would be difficult to conduct. GLP-1 medications also differ in duration of action, dose and pharmacology, while patients vary in treatment duration, underlying diabetes, gastrointestinal symptoms and other risk factors.
A 2025 multidisciplinary consensus statement from the Society for Perioperative Assessment and Quality Improvement noted that published recommendations continue to vary substantially regarding both medication management and fasting protocols. Its recommendations were therefore developed through systematic review and multidisciplinary consensus while acknowledging the limitations of the available evidence [3].
This is precisely why rigid rules are increasingly being replaced by risk stratification.
What this means for perioperative practice
Perhaps the most important practical change is occurring before the patient ever enters the operating room.
Clinicians need to ask specifically about GLP-1 and dual GLP-1/GIP medications during the preoperative assessment. Some patients may think of these primarily as weight-loss treatments rather than medications relevant to anesthesia and may not volunteer their use unless specifically asked. Australian/New Zealand guidance explicitly highlights this issue [4].
Once identified, the anesthesiologist can consider the indication for therapy, dosing schedule, treatment phase, gastrointestinal symptoms, other conditions affecting gastric emptying, type of procedure and planned anesthetic.
The goal should not be automatic cancellation. Instead, the modern approach is increasingly one of recognition, risk stratification and mitigation.
For a stable patient on long-term therapy without concerning features, continuing medication may be reasonable under current U.S. and UK recommendations. A patient early in dose escalation with significant nausea and abdominal distension represents a very different clinical scenario. The anesthetic technique, airway strategy, dietary preparation, availability of gastric ultrasound and urgency of the procedure can all influence the final decision [1].
A moving target
The perioperative story of GLP-1 receptor agonists demonstrates how quickly medical practice can evolve when widespread adoption of a new therapy intersects with an uncommon but serious anesthetic complication.
The pendulum has already moved from routine medication withholding toward a more individualized approach. Across current U.S., UK and Australian/New Zealand recommendations, a common theme is emerging: identify GLP-1 use early, assess aspiration risk carefully, and tailor perioperative management to the patient rather than relying on medication cessation alone.
For anesthesiologists, surgeons and proceduralists, staying current will be essential. For patients, the most important message may be much simpler: tell your perioperative team that you are taking a GLP-1 medication well before the day of your procedure.
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