Incretin pathway mapEvidence overview
Retatrutide: visual evidence map
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Research library
RetatrutidePublished 2026-04-23Updated 2026-07-18
Retatrutide research: phase 2 evidence, phase 3 progress, and current status.
Retatrutide has published phase 2 human evidence, and Lilly reported three completed phase 3 trials by June 2026. It remains investigational and unapproved, with additional trials underway.
Direct answer
What is the current evidence and regulatory status of retatrutide?
Retatrutide has published phase 2 human evidence, and Lilly reported three completed phase 3 trials by June 2026. It remains investigational and unapproved, with additional trials underway.
Key findings
The 2023 phase 2 obesity study is published in the New England Journal of Medicine.
Lilly's June 2026 update reports that TRIUMPH-4, TRIUMPH-1, and TRANSCEND-T2D-1 were completed successfully, with additional phase 3 trials underway.
Retatrutide remains investigational and has not been approved by the FDA or any other regulatory agency.
What retatrutide is
Lilly describes retatrutide as an investigational triple hormone receptor agonist: one molecule that activates GIP, GLP-1, and glucagon receptors. It is being evaluated in Lilly-sponsored clinical trials and is not an approved medicine.
Published phase 2 evidence
The 2023 New England Journal of Medicine paper reported results from a 48-week phase 2 trial in adults with obesity or overweight. It established a peer-reviewed human evidence base and supported further clinical development.
Phase 3 progress through June 2026
Lilly's June 2026 status page reports successful completion of TRIUMPH-4, TRIUMPH-1, and TRANSCEND-T2D-1. Lilly also lists additional TRIUMPH and TRANSCEND-T2D trials as underway across obesity, type 2 diabetes, sleep apnea, pain, cardiovascular, renal, and liver-disease research questions.
Completed or published phase 3 results are evidence milestones. They do not constitute regulatory approval, and the findings apply to Lilly's investigational clinical-trial material and protocols.
The current boundary
Retatrutide has not been approved by any regulatory agency. Clinical-trial findings for Lilly's investigational molecule cannot be transferred to separately sold laboratory research material, which has different sourcing, manufacturing, documentation, and intended-use constraints.
Common questions
Is retatrutide backed by real human data?+
Yes. A phase 2 obesity trial was published in 2023, and Lilly reported results from three completed phase 3 trials by June 2026. Those studies evaluate Lilly's investigational molecule under clinical-trial protocols.
Which phase is retatrutide in?+
Retatrutide is in phase 3 development. Lilly's June 2026 update lists three successfully completed phase 3 trials and additional TRIUMPH and TRANSCEND-T2D trials underway.
Is retatrutide FDA approved?+
No. Lilly states that retatrutide remains investigational and has not been approved by the FDA or any other regulatory agency.
Do Lilly's trial results apply to research-use products?+
No. The results apply to Lilly's investigational molecule, manufacturing controls, trial protocols, and studied populations. They do not establish safety, efficacy, dosing, or medical use for separately sold laboratory research material.
Sources
Phase 2 retatrutide obesity trial · New England Journal of Medicine, 2023
PubMed entry for retatrutide phase 2 study · PubMed
Lilly retatrutide status and phase 3 update · Eli Lilly, updated June 2026
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