GLP-1 Agonists and Bariatric Surgery Impact

Glucagon-like peptide 1 (GLP-1) is a hormone that helps regulate blood glucose levels through improved insulin sensitivity and release of insulin from the pancreas, control hunger, induce satiety and plays a role in the metabolic health of a person. GLP-1 receptor agonists (GLP1-RAs) have been shown to be effective in achieving weight loss in patients with type 2 diabetes while improving blood glucose control. Bariatric surgical procedures have been shown to be effective in treating obesity as well as superior to best medical therapy for treatment of diabetes not just through restriction of calories but also through a positive impact in modifications of gut hormones, changes in circulating bile acids, modifications in the gut microflora as well as other undefined mechanisms. The combined benefits of GLP1-RAs with bariatric surgery have only been studied to a limited effect. In this randomized trial, the effects of continuation or discontinuation of GLP1-RA therapy in patients undergoing bariatric surgery will be determined. We will compare changes in weight, metabolic determinants including circulating bile acids and gut microbiome, psychological determinants of eating behavior, and adverse side effects in patients who continue vs discontinue therapy. Given differences in metabolic and clinical outcomes in patients undergoing vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass (RYGB), both surgical groups will be examined. The study will be conducted at a high volume bariatric surgical program where patients will undergo randomization at the time of final clinic visit prior to surgery to continue or discontinue GLP1-RA. It is hypothesized that participants who continue GLP1-RA therapy after bariatric surgery will lose more weight with improved blood glucose control than those who discontinue therapy. Furthermore, changes in gut microbiome and circulating bile acids, known determinants of metabolic health, will be modified to a differential extent in those who are on GLP1-RAs vs those where GLP1-RAs are discontinued. Understanding the role these medications play in not only clinical outcomes after metabolic surgery but potential metabolic mechanisms by which surgery improves patient's metabolic health could help people with obesity and type 2 diabetes make informed decisions about their treatment options as well as advise providers on the continuation of these medications in the perioperative and postoperative period.