People Thought GLP-1s Might Have This Side Effect—New Research Proves the Opposite

4 min readNew research suggests that GLP-1 medications may lower the risk of bone fracture.The findings contradict previous concerns that GLP-1s could actually raise the risk of fracture.Doctors say the reality is complicated.For all of the positives associated with going on a GLP-1, there have been plenty of fears about the potential downsides of these medications. One big one is the worry that GLP-1s may weaken bones and raise the risk of fractures as you get older. But new research suggests that the opposite is true.The study, published in JAMA Network Open, found that GLP-1s were linked to a lowered risk of bone fractures for adults with type 2 diabetes, suggesting that these medications may actually be protective for bone health as you age.Still, the takeaway is somewhat complicated. Concerns about fractures while taking GLP-1s are “reasonable, and our study does not eliminate them,” says Christopher Hamad, MD, lead study author and orthopedic surgery resident at UCLA Health.Confused as to how this might be? Doctors break down the link between GLP-1s and bone health, plus what the findings suggest going forward.Meet the experts: Richard Siegel, MD, co-director of the Diabetes and Lipid Center at Tufts Medical Center and endocrinologist at Tufts Medicine Weight & Wellness Center–Stoneham; Christopher Hamad, MD, lead study author and orthopedic surgery resident at UCLA Health; and Mir Ali, MD, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, California.What did the study find?For the study, researchers analyzed the electronic health records of nearly 134,000 American adults with type 2 diabetes who were between the ages of 50 and 90. They compared the risk of fracture in people who were new to using GLP-1s to those who were new users of DPP-4 inhibitors, which is another common type of diabetes medication.After analyzing the data, researchers found that people who took GLP-1s had a 21 percent lower risk of developing a fragility fracture (a broken bone from an injury that wouldn't normally be strong enough to break a bone) over three years compared to those who took DPP-4 inhibitors. The largest risk reductions were in fractures of the hip, femur, and spine.But it’s important to note that the drop in risk was only in patients with type 2 diabetes. A separate analysis looked at a matching group of people without diabetes and didn’t see the same results.Why might GLP-1s lower the risk of bone fractures?The study was observational, meaning the researchers found a link between using GLP-1s and a lowered risk of fracture but didn’t find that the medications were the reason behind the drop in risk. But doctors say there could be a few reasons for this association.“One possibility is that GLP-1 receptor agonists may influence inflammation and the balance between the cells that build and break down bone,” Dr. Hamad says.It’s easy to think that weight loss could lower stress on the bones and reduce the risk of fracture, but the study found these bone-boosting perks independent of the weight loss, points out Mir Ali, MD, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, California. “Other studies have seen improvements in bone health due to weight loss,” he says.Dr. Ali also suggests that lower levels of inflammation may be at play. “There also may be some other mechanism of action from these medications that can help joint and bone health,” he says.Looking ahead, Dr. Hamad says his team is continuing to study this topic to try to find more answers.Why did people think GLP-1s made bones weaker?There are a few reasons for this. “Past concern regarding an increased risk of fracture may be related to a reduction in overall bone nutrition including protein, calcium, and vitamin D from a reduction in food intake,” says Richard Siegel, MD, co-director of the Diabetes and Lipid Center at Tufts Medical Center and endocrinologist at Tufts Medicine Weight & Wellness Center–Stoneham. “As weight falls, there is a decline in lean mass, including muscle. This has been associated with bone loss.”This may also lead to general weakness in some people, especially if they don’t do strength training, Dr. Siegel says. “Weakness may contribute to loss of balance and an increased risk for falls, which would increase the risk for fracture,” he says.So, what’s the takeaway?Doctors say that the data doesn’t definitively prove that GLP-1s lower the risk of fracture. “For fracture, past data on this has not always been consistent,” Dr. Siegel says. (He points out that the American Diabetes Association standards of care say these medications have a “neutral” effect on fracture, meaning they won’t increase or decrease your risk.)But Dr. Siegel says that a lot of fracture risk depends on what people do while using GLP-1s. “For people at high risk for fracture, the focus should continue to be on optimal bone nutrition, weight-bearing exercise, including strength training and, if medication is needed, medications that have been shown in randomized controlled trials to reduce the risk for these fractures,” he says.While Dr. Siegel says you shouldn’t go on a GLP-1 solely to reduce your risk of fracture, there’s still a chance it could help support your bone health over time.Carina Hsieh, MPH, is the deputy features editor of Women’s Health. She has more than a decade’s worth of experience working in media and has covered everything from beauty, fashion, travel, lifestyle, pets, to health. She began her career as an intern in the fashion closet at Cosmopolitan where she worked her way up to Senior Sex & Relationships Editor. While covering women’s health there, she discovered her passion for health service journalism and took a break to get her Masters in Public Health. Post-grad school, she worked as a freelance writer and as The Daily Beast’s first Beauty, Health, and Wellness Reporter. Carina is an alum of the Fashion Institute of Technology and the Yale School of Public Health. She and her French Bulldog, Bao Bao, split their time between Brooklyn and Connecticut. She enjoys reformer Pilates, (slow) running, and smelling the fancy toiletries in boutique fitness class locker rooms.