GLP-1 conversations typically focus on weight, blood sugar, and hearts. Joints, a topic very close to my heart, or, um, knees, barely come up. But at ACR Convergence 2026, the American College of Rheumatology’s annual meeting in Orlando, that started to change. New data were presented on what happens to people with autoimmune arthritis such as rheumatoid arthritis (RA) and psoriatic arthritis (PsA) after they start semaglutide or tirzepatide.
What the Registry Data Found
The first study looked at real-world records from a large national rheumatology registry. Researchers identified nearly 17,000 patients with RA or PsA who started a GLP-1, about two-thirds with rheumatoid arthritis and 80% women, with an average age of 58.
They zeroed in on 1,880 patients with complete checkups before starting the medication and again one year later. Over that year, those patients lost an average of about 15.6 pounds, and their scores on RAPID3, a standard questionnaire that captures joint pain, physical function, and overall well-being, dropped by an average of 1.3 points.
More Weight Lost, Better Joint Outcomes
The more interesting finding was the dose-response pattern (the more you lose, the bigger the effect). For every 5% of body weight lost, RAPID3 scores fell by another 0.30 points, and each 5% of weight loss raised the odds of a clinically meaningful improvement by 14%.
The biggest gains showed up in pain and in patients’ overall assessment of how they were doing, and the pattern looked similar in RA and PsA. In other words, the more weight people lost, the better they felt.
What This Study Can’t Tell Us
It’s worth being clear about what that study can and can’t say. Keep in mind this study was retrospective and observational. In addition the abstract presented at the conference isn’t a published paper yet, and followed only the subset of patients with complete follow-up data.
In other words, it shows an association between weight loss and feeling better, not proof that the weight loss caused the improvement. It can’t separate the effect of the pounds lost from any direct effect of the drugs themselves.
The Fat and Inflammation Tangle
That second question is exactly what the second session tackled. Dr. Veena Ranganath, a rheumatologist at UCLA, laid out why obesity and inflammatory arthritis are so tangled. Fat tissue isn’t inert. It behaves like an endocrine organ, pumping out inflammatory signaling molecules that create what she calls a “low-grade hum of inflammation,” and that hum raises the risk of conditions like RA and PsA.
Once someone has the disease, they enter into a painful loop. The extra weight tends to make it worse, with more pain, more disability, and a weaker response to treatment. Studies show a high BMI is associated with 60% higher odds of a TNF inhibitor, one of the most common classes of biologic drugs used for these conditions, failing.
Dr. Ranganath argues that weight loss by any route helps, but GLP-1s may add something beyond weight loss. GLP-1 receptors sit on immune, blood vessel, and nerve cells, and the clinical signals include lower CRP, a key inflammation marker, along with fewer major cardiovascular events.
Something Beyond Weight?
The strongest evidence for that “something extra” comes from a pair of Eli Lilly-sponsored phase 3b trials, TOGETHER-PsA and TOGETHER-PsO, which tested tirzepatide alongside the biologic ixekizumab in patients with psoriatic disease and obesity. See my earlier post, The GLP-1 Inflammation Drop That Led Me to Drop My Cane, for more on this topic.
In the psoriatic arthritis trial, 271 adults with an average BMI around 37.6 received either ixekizumab alone or ixekizumab plus tirzepatide. At 36 weeks, 33.5% of patients on the combination reached ACR50, a 50% improvement in disease activity, compared with 20.4% on ixekizumab alone.
They also improved on fatigue, physical function, and quality of life. The detail that caught researchers’ attention was the timing. The two groups began to separate as early as week 4, before anyone had lost a meaningful amount of weight. Lilly’s later 52-week topline data suggested the gap widened over time, though those results haven’t yet been through full peer review.
Good to Know
There are things to keep in mind here, too. TOGETHER-PsA was open-label, meaning patients knew they were getting tirzepatide. Knowing that could affect how they felt about the treatment. Also, the company that makes both drugs sponsored the trials, and Dr. Ranganath herself reports relationships with Lilly. None of that makes the findings invalid, but it’s important context.
One piece of practical wisdom from her talk is worth passing along because it’s rarely discussed. GLP-1 side effects like nausea, fatigue, and diarrhea overlap heavily with side effects from common arthritis drugs, particularly methotrexate. (As a former methotrexate user, I can confirm.)
The Side-Effect Overlap
When a patient on both calls with stomach trouble, it’s hard to know which medication is responsible, and the one the patient wants to quit is rarely the GLP-1. Her rule of thumb is to make sure the arthritis medications are tolerable and stable first, then add the GLP-1, so you only change one thing at a time. That’s a conversation for you and your rheumatologist, not a DIY experiment.
The Access Gap
Here’s the part I want you to think about. None of the GLP-1s has an FDA indication for inflammatory arthritis. That means there’s no label to point to if you have PsA or RA and asking your insurer to pay for one. Unfortunately, these findings don’t change that overnight. But they add more names to a growing pile of conditions where evidence shows GLP-1s can make a meaningful difference. In this case, every well-designed trial that shows joint benefits makes the case for coverage a little harder to ignore.
Measuring What Patients Already Knew
I live with psoriatic arthritis and osteoarthritis myself, so I read all of this with more than professional interest. For years, people in this community have reported that their joints felt better on these medications, often before the scale had even moved much. It’s exciting to finally watch researchers start measuring what patients have been telling each other all along.
Sources:
Biscaldi, L. (2026, November 8). Addressing obesity in inflammatory arthritis: The role of GLP-1 RAs. Rheumatology Advisor. https://www.rheumatologyadvisor.com/reports/glp-1-inflammatory-arthritis-obesity/
Eli Lilly and Company. (2026, March 28). Phase 3b data presented at AAD Annual Meeting show Lilly’s Taltz (ixekizumab) plus Zepbound (tirzepatide) delivered superior efficacy for adults with psoriatic arthritis and obesity [Press release]. PR Newswire.
Healio. (2026, June 9). Taltz plus tirzepatide superior to monotherapy in psoriatic arthritis alongside obesity.
Klein, A. (2026, November 8). GLP-1 RAs improve patient-reported outcomes in rheumatoid, psoriatic arthritis. Rheumatology Advisor.
Merola, J. F., Mease, P., Kivitz, A., et al. (2026). Ixekizumab with tirzepatide achieved greater disease control than ixekizumab alone in adults with psoriatic arthritis and overweight or obesity: Results from a randomized clinical trial. Arthritis & Rheumatology, 78(10), 2089–2101. https://doi.org/10.1002/art.70134
Moura, C., McCormick, N., Zhang, J., Holladay, E., Xie, F., Mehta, T., Baker, J., & Curtis, J. (2026, November 6–11). Weight loss following GLP-1 receptor agonist initiation is associated with improved patient reported outcomes in rheumatoid arthritis and psoriatic arthritis [Conference presentation, Abstract 0867]. ACR Convergence 2026, Orlando, FL.
Practical Dermatology. (2026). Combination therapy improves outcomes in psoriatic arthritis with obesity.
Weintraub, M., & Ranganath, V. (2026, November 6–11). GLP-1 receptor agonists: Perspectives on use in autoimmune inflammatory rheumatic diseases [Conference presentation]. ACR Convergence 2026, Orlando, FL.
