The most extensive research to-date into the diabetes drug exenatide for the treatment of Parkinson’s showed that the medication does not slow progression of the disease.
The study, published in the February 4, 2025, issue of The Lancet, looked at exenatide, which is one type of GLP-1 receptor agonist. More research is needed to determine if other forms of GLP-1 medications, which may act differently, can provide a benefit, or if certain populations would have better results. But these results, from a Phase III trial, effectively close the door on the idea of exenatide as a treatment for Parkinson’s.
GLP-1 Agonists and Parkinson’s Disease
GLP-1 receptor agonists (such as Wegovy and Ozempic) were formulated to treat type 2 diabetes and aid in weight loss. GLP-1 is a natural hormone in the body that affects insulin production and appetite. There is some evidence that insulin signaling is altered in diseases like Parkinson’s and Alzheimer’s. Whether drugs that mimic GLP-1 might provide a benefit through this or other mechanisms, like reducing inflammation, has been an active area of research.
Results of the Exenatide Phase 3 Trial
In a Phase III trial, 194 people with moderate severity Parkinson’s disease (meaning people who can generally move easily without assistance while on their dopamine medications) received an injection of either exenatide or a placebo for 96 weeks. It was the largest and longest study to date of a GLP-1 receptor agonist in people with Parkinson’s disease, and was conducted across six research hospitals in the U.K. The study concluded in summer 2024.
The study aimed to test whether regular administration of exenatide could slow or stop progression in people with Parkinson’s. Results from the trial indicated there was no evidence that exenatide slowed the progression of the disease.
Researchers are continuing to look at additional questions that might explain the range of results seen to date across multiple prior GLP-1 treatment trials in Parkinson’s. The results also point to the need for better and faster understanding of the biological effects of drugs like GLP-1 receptor agonists. This requires additional advances in Parkinson’s biomarker research and imaging — both of which are actively being pursued through research funded by The Michael J. Fox Foundation (MJFF).
The State of GLP-1 Research
The Phase 3 exenatide study is just the latest in a line of GLP-1 research. For example, in April 2024, the New England Journal of Medicine published results of a Phase II clinical trial of a diabetes drug and GLP-1 receptor agonist lixisenatide, testing whether the medication could slow progression of PD.
That study showed that people treated with lixisenatide held largely steady in their test score, while the control group taking a placebo treatment continued to progress with the disease. The difference between the two groups was small, but comparing these with findings of all research into GLP-1 drugs for Parkinson’s show more work is needed to understand what is driving conflicting trial results and whether targeting the GLP-1 pathway can offer any benefits to people with Parkinson’s.
What Comes Next?
Science continues to explore the potential of these drugs in Parkinson’s. There are additional formulations still to test and controlling study populations carefully could reveal specific groups of participants who might respond better to these therapies than others. Results of some of these studies are due in 2025.
Overall, MJFF has supported more than a dozen GLP-1 projects since 2007, totaling roughly $5 million dollars, including the Phase II exenatide trial that inspired the Phase III that is now returning results. There are many more medications currently being investigated. MJFF is at the helm of that robust treatment pipeline, with the Foundation monitoring progress on more than 150 drugs and therapies in clinical trials.