Bariatric Surgery Outperforms GLP-1s for Type 2 Diabetes in New Study

When endocrinologist Mary Elizabeth Patti looks at a patient with type 2 diabetes who could benefit from weight loss, she sees more than body mass index and blood glucose levels. She also recognizes the challenges of social vulnerability, understanding how low income, food insecurity, and limited access to health care might matter in treatment choice. After all, those factors are strongly linked to developing type 2 diabetes and obesity in the first place. For more than a dozen years, Patti has been a leader of long-running randomized clinical trials conducted in four U.S. cities that compared bariatric surgery to medication and lifestyle management for type 2 diabetes. In 2024, one of those trials demonstrated the superiority of bariatric surgery for patients, measured by lower blood glucose levels, higher weight loss (28% vs. 10%), less use of diabetes medications, remission of diabetes to the point of no longer needing to inject insulin, and reduced risk factors for cardiovascular disease. Advertisement In a new secondary analysis of the larger trial published Monday in the Annals of Internal Medicine, Patti and her colleagues asked how different social determinants of health affected outcomes after bariatric surgery compared to medical therapy for people with type 2 diabetes and obesity. Bariatric surgery was better than medical therapy across all social backgrounds, they found, and not just in areas of higher deprivation. The ancillary study was smaller, and some of the participants randomized in earlier stages crossed over from medical to surgical treatment, and the reverse. The authors acknowledged and accounted for these limitations, along with the rapid development of more powerful obesity drugs not fully captured in the study. Still, “Bariatric surgery remains an underutilized approach. Even in comparison to these really wonderful medications that we now have access to, it is still better,” Patti, an endocrinologist and director of the hypoglycemia clinic at Joslin Diabetes Center in Boston, told STAT. “I’m not a surgeon, but I think we need to keep in mind that surgery offers an approach which can be a durable therapy for type 2 diabetes and obesity.” Advertisement At the overall study’s start, carried out in Boston, Cleveland, Pittsburgh, and Seattle, 355 participants were randomly assigned to undergo medical therapy or one of three surgical approaches: gastric bypass, sleeve gastrectomy, or adjustable gastric lap banding. Medical and lifestyle interventions, based on the well-known Diabetes Prevention Program, included individualized nutrition counseling and instruction on exercise and how to monitor glucose. As time passed, fewer people chose lap band surgery, which has now fallen out of favor, and newer obesity drugs were increasingly available in the trials’ later stages. Some people from the medication group later chose surgery, and some people who’d had surgery began taking obesity drugs. By year 12, more than a third of participants in the medical therapy groups and more than a quarter in the surgical groups were receiving incretin-based therapy, the class of drugs that includes older ones like liraglutide (sold as Saxenda) as well as newer GLP-1s like tirzepatide (sold as Mounjaro). The smaller study analyzed data from 258 adults with type 2 diabetes who began the larger trial having either undergone bariatric surgery or received medical and lifestyle therapy. They had been sorted by their ZIP codes to identify the Area Deprivation Index for where they lived. Their weight and hemoglobin A1c levels, which measure blood glucose, were tracked for seven to 12 years. While there was a trend toward better outcomes from surgery for people living in a high deprivation area, it was not statistically significant, Patti said. Navigating diabetes care alone is hard, she said, particularly when combined with socioeconomic challenges. Patients are asked to modify their diets, perhaps in ways tough on family food budgets. Exercise is important, but not always feasible for people working two jobs to make ends meet. Then there’s the medical environment, where it’s difficult even for insured people to maintain access to medications and keep taking them consistently. “If you don’t have an advocate in the health care system and you really don’t have a way to keep up with the need for approvals or prior authorizations, being an advocate for yourself — that’s really hard when you are having many social, financial and other stressors,” Patti said. Advertisement Amid the enthusiasm for all things GLP-1, surgery may not be top of mind for these patients, whatever their socioeconomic circumstances. Neither approach is easy. One dividing line: If someone hopes to lose 100 pounds, that’s more likely with surgery than with medications. “There’s so many more options now for people, which is great. And people might end up needing more than one modality,” Melanie Jay, a professor of medicine and population health at New York University who is also director of the NYU Langone Comprehensive Program on Obesity Research, said in an interview. She was not involved in the study. “Obesity is a disease that often needs to be managed lifelong. We don’t have a cure yet, right?” The biology behind the success of surgery or medical therapy is remarkably similar, something that may be lost in the rush to develop pills to replace injectable medications. Surgery reduces appetite, too, changing the way nutrients interact with the intestine and resulting in increased secretion of — you guessed it — GLP-1 hormones after a meal. These hormones plus weight loss improve diabetes control. “You’re not stopping medications because of side effects or because your insurance company is not paying for it anymore,” Patti said. “So it’s a sustained way to activate the same intestinally derived mechanisms that intersect with the brain to change appetite and metabolism.” Jason Samuels, a professor of surgery at Vanderbilt, argues that all therapies for obesity remain underused. Bariatric surgery, despite its track record for safety, effectiveness, and long-term durability, reaches a very small percentage of patients who qualify, he said, and medications don’t help all the people who could benefit. He was not involved in the study, which he called an important evaluation, even if outpaced by newer drugs. “Looking ahead, next-generation incretin-based agents may narrow the gap for some patients, but real-world durability, tolerability, adherence, and — critically — affordability and access will determine how closely medications can match surgical outcomes across diverse populations,” he said via email about obesity drugs. “Ultimately, we need large, long-term, well-designed studies to clarify the best strategy for a given patient.” Advertisement Patti wants surgery to still be in the discussion. “We can look at epidemiology and large population studies, and they all show that bariatric surgery is more effective at improving diabetes control, improving diabetes remission, reducing complications, and prolonging survival,” she said. “But you know, when we’re talking to an individual patient, the question is, what’s the best choice for that particular patient?”