OR09-05 Perioperative Weight Loss With GLP-1 Receptor Agonists in Patients Receiving Bariatric Surgery

Abstract Disclosure: A. Rao: None. B. Ruhle: None. M. Ono: None. J.O. Chinn: None. P. Ruhi-Williams: None. L. Kennedy: None. M.M. Esquivel: None. M.E. Hauser: None. D.E. Azagury: Consultant: Form Health, GI Windows, Endolumik. D. Desai: None. Introduction: While bariatric surgery is the most effective tool for weight loss, the role of glucagon-like peptide 1 receptor agonists (GLP-1) in addition to bariatric surgery is underexplored. This study investigates weight loss outcomes in patients on GLP-1 who receive bariatric surgery, with a focus on the perioperative period. Methods: We conducted a retrospective analysis of all metabolic/bariatric surgical procedures performed at Stanford Health Care between January 1, 2019, and December 31, 2023. Adults with obesity who underwent sleeve gastrectomy or gastric bypass were identified and stratified into treatment groups based on the GLP-1 or GLP-1/glucose-dependent insulinotropic polypeptide (GIP) RA prescribed (semaglutide, liraglutide, dulaglutide, and tirzepatide) and the timing of prescription in relation to their operation. Patients who were on GLP-1 prior to the study period, were prescribed but who did not receive the medication, or were on GLP-1 for <4 months all were excluded. Patients were grouped as follows: Group 1) patients prescribed GLP-1 within 2 years before surgery, but not after; Group 2) patients prescribed GLP-1 within 2 years after surgery, but not before; Group 3) patients prescribed GLP-1 both within 2 years before surgery and 2 years after surgery. Patients not prescribed GLP-1 were included as the control group. The primary outcome was percent total body weight loss. Results: There were 846 patients who received bariatric surgery during the study interval, and 568 met inclusion criteria. There were 424 patients in the control group, 32 patients in Group 1, 66 patients in Group 2, and 46 patients in Group 3. Patients in Group 3 had a significantly higher starting BMI compared to other groups. Patients in Group 2 and Group 3 achieved significantly more total body weight loss than Group 1 and control (30.7% and 32.7%, respectively, vs 28.8% in Group 1, and 27% in the control group, p-value = 0.0002). Discussion: The results underscore the synergistic potential of combining GLP-1 RA with bariatric surgery in achieving greater weight loss in the perioperative period. GLP-1 usage in the perioperative period may prime patients for more effective weight loss, potentially by inducing behavior/physiologic changes that complement the metabolic effect of surgery. Patients with very severe obesity likely benefit the most from starting GLP-1 in the preoperative setting and continuing postoperatively. However, if starting BMI is relatively lower, post-operative GLP-1 alone is effective in augmenting weight loss. Conclusion: Patients on GLP-1 receptor agonists both preoperatively and postoperatively relative to bariatric surgery experienced the greatest weight loss. While existing studies have focused on the use of GLP-1 primarily for weight regain, our findings highlight their potential as adjunctive therapy for weight loss during the critical perioperative period. Presentation: Saturday, July 12, 2025