New research presented at the annual meeting of the American Academy of Orthopaedic Surgeons suggests a potential link between prolonged use of GLP-1 medications and an increased risk of developing bone and joint conditions such as osteoporosis, gout, and osteomalacia. While the study emphasizes that it only shows associations and does not prove causation, and has not yet undergone peer review, its findings contribute to an expanding body of research exploring the impact of these medications on skeletal health.

The genesis of this investigation emerged from clinical observations by orthopedic surgeon and study author John G. Horneff. He noted that patients undergoing GLP-1 therapy appeared to experience significant tendon injuries following relatively minor incidents. This observation prompted a critical question from fellow author Muaaz Wajahath, a medical student at Michigan State University: whether GLP-1 therapy and the rapid changes in body composition it induces might more broadly affect connective tissue and bone. To delve into this, researchers analyzed extensive data from a large, multi-institutional medical records database.

The study encompassed 73,483 adult participants who were taking GLP-1 medications, including widely recognized drugs such as semaglutide (Ozempic, Wegovy), liraglutide (Victoza), dulaglutide (Trulicity), and exenatide (Byetta). This group was meticulously compared against an equal number of adults who were not on these medications. Health outcomes for both cohorts were tracked over a five-year period following the initiation of treatment. The primary focus was to compare the incidence rates of osteoporosis, characterized by weak bones prone to fracture; gout, an inflammatory arthritis resulting from excess uric acid crystals in the joints; and osteomalacia, which involves the softening of bone tissue.

After a rigorous comparison of diagnoses between GLP-1 users and nonusers, and controlling for various confounding factors including age, sex, race, body mass index (BMI), hemoglobin A1c levels, tobacco use, and certain underlying health conditions, researchers identified statistically significant differences. Over the five-year study duration, the findings revealed a marked disparity: 4.1% of GLP-1 users received an osteoporosis diagnosis, compared to 3.2% of nonusers, indicating approximately a 29% higher risk. For gout, 7.2% of GLP-1 users were diagnosed, versus 6.6% of nonusers, signifying about a 12% higher risk. The most substantial proportional increase was seen in osteomalacia, with 0.2% of GLP-1 users receiving this diagnosis compared to 0.1% of nonusers, representing an alarming 2.55-fold higher risk.

Dr. Andres Splenser, an endocrinologist at Memorial Hermann, remarked that these findings add crucial data to the ongoing discourse surrounding GLP-1 use and bone health. He highlighted that prior research on this topic has been "mixed and limited," with some studies noting minor increases in bone turnover markers—even prompting exploration into GLP-1s' potential role in osteoporosis treatment—while others have shown either no change or only transient shifts. Dr. Splenser cited a 2024 study, for example, which demonstrated that while GLP-1 therapy alone was associated with reduced bone mineral density in the hip and spine, the inclusion of resistance exercise effectively mitigated and fully offset this loss.

The precise mechanisms linking GLP-1 use to these bone and joint health concerns remain unclear, but experts have put forth several theories. One prominent hypothesis posits that rapid weight loss, rather than the medication itself, could be a contributing factor to increased osteoporosis risk. Dr. Kyle J. Thompson, a bariatric surgeon at Intermountain Health, explained that the mechanical stress of carrying weight typically helps stimulate bone growth. Consequently, if weight is lost too quickly, the body's rate of bone breakdown might surpass its capacity for rebuilding. Another theory, articulated by Dr. Sonia Gibson, an endocrinologist at Allara Health, suggests that rapid fat breakdown can temporarily elevate circulating uric acid levels, which in turn can precipitate gout flares. Dehydration, often a side effect of the gastrointestinal issues associated with GLP-1s, may also exacerbate gout. Furthermore, Dr. Thompson added that patients on GLP-1s, due to reduced appetite, might consume less food overall, potentially leading to deficiencies in essential bone-supporting nutrients such as calcium, protein, and vitamin D.

It is important to approach these new research findings with several significant caveats. The study design did not allow researchers to track crucial variables such as medication dosage, adherence rates, the use of supplements, or various lifestyle factors including diet, exercise routines, and alcohol intake. Additionally, individual bone mineral density or the occurrence of fractures were not directly measured. Crucially, the study merely establishes associations and does not definitively prove that GLP-1 medications are the direct cause of these conditions.

For the vast majority of individuals, these findings should not prompt a discontinuation of GLP-1 therapy, as Dr. Gibson emphasized. She stated that "For most patients, this small risk is unlikely to outweigh the heart and metabolic benefits of the medication." Instead, the research underscores the paramount importance of maintaining good nutrition, ensuring adequate intake of bone-supporting nutrients like calcium and vitamin D, engaging in regular strength training, and continuously monitoring bone health during periods of significant weight loss. Ultimately, using GLP-1s under the careful supervision of a physician, who can monitor for potential side effects and these low-risk considerations, remains key, as Dr. Splenser concluded.