The GLP-1 idea: can diabetes drugs slow Parkinson's?

The research record

This is the project's file for this landmark, as written and checked. Sources are listed at the end; anything not yet confirmed is marked "Not yet verified".

Who

Dilan Athauda, Tom Foltynie, Nigel Greig and colleagues at UCL (2017); Wassilios Meissner and Olivier Rascol (2024); Nirosen Vijiaratnam, Foltynie and colleagues (2025).

What happened

It began with a 44-person trial with no placebo (landmark 101), chosen for testing through the Cure Parkinson's Trust's drug-repurposing committee (landmark 119). Then came the controlled trials.

• Athauda 2017 (exenatide, Phase 2): 62 people, 48 weeks of once-weekly exenatide, with a 12-week washout and the main endpoint at week 60. Off-medication motor score (MDS-UPDRS III) improved by 1.0 point on exenatide and worsened by 2.1 on placebo; adjusted difference −3.5 points (95% CI −6.7 to −0.3, p=0.0318). Lancet 390:1664.
• Lixisenatide 2024 (Phase 2, 156 people): motor decline about 3 points less than placebo over a year (landmark 141).
• Exenatide 2025 (Phase 3, 194 people): no benefit over placebo (landmark 142).
• After the Phase 3: NLY01 missed its Phase 2 goal (landmark 143); semaglutide (landmark 189), PT320 (landmark 309) and the Stockholm exenatide PET trial (landmark 310) have their own files.

Why it moved us toward a cure

It was the first large programme to test a repurposed drug for slowing Parkinson's, built on preclinical neuroprotection data, and it showed how hard it is to move from a positive Phase 2 to a positive Phase 3.

Outcome

Open, mostly negative. One review suggests possible reasons for the divergence: how much of the drug reaches the brain, a subgroup with insulin resistance, shorter disease duration in the Phase 3, placebo effects in motor scoring, and benefit that may reflect symptom effects rather than slowing. That review's author has a conflict of interest (a competing developer). A planned Phase 3 of lixisenatide was reported in 2024 but not confirmed in 2026. The Parkinson's Foundation does not currently recommend GLP-1 drugs for Parkinson's without diabetes or obesity.

Sources

• Athauda et al., Lancet 2017, DOI 10.1016/S0140-6736(17)31585-4 (numbers via MDedge)
• Frontiers 2026 review · Parkinson's Foundation
• Meissner 2024 and Vijiaratnam 2025 sources are in landmarks 141 and 142; Stockholm and PT320 in 310 and 309.
• Not yet verified: the lixisenatide Phase 3 status; ClinicalTrials.gov status pages would not load at the last check.