Full stomach despite fasting: GLP-1s, sedation and the 2024 reversal

Why it affects every practice

GLP-1 agonists slow gastric emptying; tirzepatide does so transiently, much like selective long-acting GLP-1 agonists¹⁰. That is part of how they work, and also a problem whenever a patient arrives for endoscopy, sedation or cosmetic surgery with a supposedly empty stomach. The tirzepatide label itself mentions "rare postmarketing reports of pulmonary aspiration" and admits the available data "are insufficient to inform recommendations to mitigate the risk"⁹. One of the first published cases, in 2023, described abundant gastric contents and intraoperative pulmonary aspiration in a patient on semaglutide despite 18 hours of fasting¹³.

What the data show

A 2025 meta-analysis of 28 observational studies separated two outcomes that are often conflated. Residual gastric content: 18 studies with 165,522 patients, OR 5.96 (95% CI 3.96–8.98). Pulmonary aspiration: 9 studies with 185,414 patients, OR 1.04 (0.87–1.25), both with low certainty. Holding at least one dose was associated with less residual content (OR 0.51), with very low certainty¹.

In a BMJ cohort of 43,365 adults with type 2 diabetes undergoing upper endoscopy, comparing GLP-1 users with SGLT2 inhibitor users, aspiration was 4.15 vs 4.26 per 1,000 (RR 0.98), but aborted procedures doubled: 9.79 vs 4.91 per 1,000 (RR 1.99)². In a study of 84 matched pairs undergoing endoscopy, residual content was 13.1% vs 4.8% (aOR 4.62), with worse mucosal visibility⁵.

Gastric ultrasound: the uncomfortable finding

A 2026 prospective multicenter study scanned the stomachs of 44 semaglutide users and 44 matched controls before elective surgery. "Full stomach": 49% vs 18% (OR 4.29). Solid contents: 42% vs 7% (OR 9.85). The authors conclude the risk remains elevated even after one semaglutide dose is withheld³. In a retrospective series published in the Canadian Journal of Anesthesia, visible content was 19% vs 5% (aOR 5.8), with 5 emergency intubations vs 1 and one aspiration⁴. Earlier, in 124 patients assessed with gastric ultrasound in Houston, increased gastric content was 56% on weekly GLP-1 agonists vs 19%, with no association with how long the drug had been held¹².

A practical detail: in an upper-endoscopy series, the risk of solid content (OR 3.80) was not increased when colonoscopy was done the same day, presumably because the patient had followed the liquid diet of bowel prep⁶. A Brazilian retrospective study found the same: increased residual content in 24.2% on semaglutide vs 5.1%, and a protective effect when endoscopy was combined with colonoscopy (OR 0.25)¹¹.

How the guidance changed

In June 2023 the American Society of Anesthesiologists advised: "Hold GLP-1 agonists a week prior to the procedure/surgery for patients who take the medication weekly"⁷. In November 2023 the AGA published its own rapid clinical practice update for endoscopy¹⁵. In October 2024 a joint statement from ASA, AGA, ASMBS, ISPCOP and SAGES changed course: "Most patients should continue taking their glucagon-like peptide-1 (GLP-1) receptor agonists before elective surgery", and patients at high GI risk "should follow a liquid diet for 24 hours before the procedure"⁸.