Retatrutide (LY3437943) has progressed into an extensive Phase 3 clinical development programme investigating its efficacy and safety across obesity, overweight, type 2 diabetes and several associated health conditions.
Developed by Eli Lilly, retatrutide is an investigational GIP, GLP-1 and glucagon receptor agonist. Unlike medicines that target a single incretin pathway, retatrutide has been designed to activate three metabolic receptor systems within one molecule. The scientific rationale behind this approach is explored in our guide to the triple-agonist hypothesis.
The Phase 3 TRIUMPH programme includes multiple large-scale studies designed to examine retatrutide across different populations and clinical settings. This represents the latest stage in a development programme that has progressed through early human research and Phase 2 studies. See our timeline of retatrutide’s investigational development for a broader overview.
TRIUMPH-1 evaluated retatrutide in adults with obesity or overweight and at least one weight-related comorbidity without diabetes. The study also incorporated research involving participants with knee osteoarthritis and obstructive sleep apnoea. Lilly reported positive topline Phase 3 results from TRIUMPH-1 in May 2026.
TRIUMPH-2 focused on adults with obesity or overweight and type 2 diabetes, while TRIUMPH-3 studied participants with severe obesity and established cardiovascular disease. Lilly announced positive topline results from both trials in July 2026.
The research programme extends beyond these initial studies. TRIUMPH-5 is directly comparing retatrutide with tirzepatide in approximately 800 adults with obesity, while TRIUMPH-6 is investigating the maintenance of weight reduction. Other studies are examining populations with conditions including chronic low back pain.
One of the largest components is TRIUMPH-Outcomes, a Phase 3 study involving approximately 10,000 participants. It is designed to investigate cardiovascular and kidney outcomes in adults living with obesity and established atherosclerotic cardiovascular disease and/or chronic kidney disease. The study is expected to continue into 2029.
This broader programme is important because Phase 3 research examines considerably larger and more diverse populations than early-stage studies. Researchers can assess efficacy while accumulating substantially more information about safety, tolerability and outcomes across different participant groups.
Although several Phase 3 studies have now produced topline findings, other trials remain ongoing. Detailed results from individual studies may also undergo presentation at scientific meetings and publication in peer-reviewed journals. Our retatrutide clinical trial overview provides further information about the different stages of the clinical research programme.
Retatrutide therefore remains an investigational compound. It has not been approved by regulatory agencies, and ongoing Phase 3 research continues to define its efficacy and safety profile.
For researchers, the expanding programme provides an increasingly detailed picture of how simultaneous GIP, GLP-1 and glucagon receptor agonism behaves across different metabolic and cardiometabolic research settings. For further educational material, visit the Retatrutide Knowledge Centre.
Timeline: 2023–present | Large-scale Phase 3 programme
Disclaimer: Retatrutide is an investigational compound and is not currently approved as a medicine in the UK. This content is provided for scientific and educational purposes only.
Educational summary of publicly reported research. Not a therapeutic claim and not medical advice. Retatrutide is investigational and not approved for human use in most jurisdictions.
Mid-stage investigational trials explored a range of retatrutide doses and metabolic endpoints in adults with obesity, with results…
Initial investigational studies characterised the pharmacokinetics and tolerability of retatrutide (LY3437943), establishing the groundwork for later dose-ranging research.