Retatrutide: clinical evidence record
Also known as: LY3437943
Oliver Mackman · Editorial director · Best Business Loans Ltd (16833937)
Last updated 2026-05-22
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AI-friendly summary · Retatrutide
Eli Lilly investigational compound (LY3437943). Phase 2 trial data reports double-digit body-weight reduction at 48 weeks. Phase 3 TRIUMPH programme is in progress. Not licensed in any jurisdiction.
Mechanism of action
How Retatrutide works
Synthetic peptide acting as a triple agonist at three distinct receptors simultaneously: GLP-1, GIP, and glucagon. Combines appetite suppression, insulin sensitivity, and glucagon-mediated energy expenditure in a single molecule.
Top peer-reviewed citations
Selection of the most-cited peer-reviewed literature on Retatrutide. Where a verified PMID or DOI is shown, the citation links to the original record. Other citations list the title, authors, journal and year so the reader can locate the paper through the journal index or the PubMed search linked below. PeptideClear publishes editorial commentary, not clinical guidance.
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Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial
Jastreboff AM, Kaplan LM, Frias JP, et al.. The New England journal of medicine, 2023.
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Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA
Rosenstock J, Frias J, Jastreboff AM, et al.. Lancet (London, England), 2023.
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LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept
Coskun T, Urva S, Roell WC, et al.. Cell metabolism, 2022.
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Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial
Sanyal AJ, Bedossa P, Fraessdorf M, et al.. Nature medicine, 2024.
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Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial
Coskun T, Wu Q, Schloot NC, et al.. The lancet. Diabetes & endocrinology, 2025.
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Decreases in circulating ANGPTL3/8 concentrations following retatrutide treatment parallel reductions in serum lipids
Wen Y, Lemen D, Lin Y, et al.. Diabetes, obesity & metabolism, 2025.
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Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials
Giblin K, Kaplan LM, Somers VK, et al.. Diabetes, obesity & metabolism, 2026.
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Rationale, design and baseline characteristics of the TRANSCEND-CKD trial of retatrutide in patients with chronic kidney disease
Heerspink HJL, van Raalte DH, Bjornstad P, et al.. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, 2026.
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Appetite, eating attitudes, and eating behaviours during treatment with retatrutide in adults with type 2 diabetes: Results of a phase 2 study
Kanu C, Boye KS, Poon JL, et al.. Diabetes, obesity & metabolism, 2025.
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Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial
Bajaj HS, Welch M, Shah P, et al.. Lancet (London, England), 2026.
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Synergistic Intervention for Obesity: Integrating Central Appetite Regulation and Peripheral Energy Expenditure
Xie J, Yang Y, Chen W, et al.. Current obesity reports, 2026.
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A Hydrophobic Tag-Assisted Liquid-Phase Strategy for the Synthesis of Retatrutide
Mao CY, Pang ZJ, Qiao GY, et al.. Organic letters, 2026.
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Retatrutide: Triple acting jab for type 2 diabetes lowers blood sugar and boosts weight loss, trial reports
Lang K. BMJ (Clinical research ed.), 2026.
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Do GLP-1 Receptor Agonists Sabotage Fat Grafts? : A Scoping Review of GLP-1 Receptor Agonist Effects on Adipocyte Biology and Implications for Autologous Fat Transfer
Chalhoub X, Yang Ng Z. Aesthetic surgery journal, 2026.
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Beyond weight loss: multisystem benefits of obesity medications
Savas M, Kuckuck S, Boon MR, et al.. The lancet. Diabetes & endocrinology, 2026.
Full PubMed search: https://pubmed.ncbi.nlm.nih.gov/?term=retatrutide+LY3437943.
Registered clinical trials
As of 2026-07-13, Retatrutide has 33 interventional trials listed on ClinicalTrials.gov and the ISRCTN registry. Registration means a study is planned, running or completed. It is not evidence of efficacy, and a listing is not an endorsement.
Source: ClinicalTrials.gov and the ISRCTN registry, refreshed 2026-07-13. See the peptide clinical-trials tracker for the full picture across compounds.
UK regulatory status
Plain-English summary of where Retatrutide sits under the four UK and international frameworks that govern peptide supply. Editorial commentary, not legal advice.
- Misuse of Drugs Act 1971: Not controlled under the Misuse of Drugs Act 1971.
- Psychoactive Substances Act 2016: Not scheduled under the Psychoactive Substances Act 2016.
- MHRA medicines classification: No UK marketing authorisation as a medicine.
- WADA Prohibited List: Not currently listed on the WADA Prohibited List.
Full regulatory record: Retatrutide UK regulatory status.
Risks and unknowns
What the literature does not yet show about Retatrutide
Known concerns
- Retatrutide has been studied in randomised human trials, which is a materially stronger position than most compounds on this site. Trial populations, endpoints and durations are still narrower than everyday use, so results describe the trial, not every person.
- 33 registered interventional trials exist for Retatrutide and 14 are recruiting, so the evidence base is actively moving. A registration is not a result, and a recruiting trial has by definition not reported.
- Retatrutide holds no UK marketing authorisation, so nothing you can buy has been assessed by a regulator, released by batch, or dispensed by an accountable pharmacy. Purity, dose accuracy and sterility rest entirely on the seller's own documentation.
Open questions in the literature
- Long-term outcomes beyond the duration of the published trials are unknown, and the published trials are considerably shorter than the periods over which people actually use these compounds.
- Interactions between Retatrutide and prescribed medicines are not systematically studied, which matters most for anyone already on treatment for a long-term condition.
- Effects on body composition, and whether any change is maintained after stopping, are among the least well characterised parts of the metabolic literature.
Regulatory note
No UK marketing authorisation as a medicine. Not currently listed on the WADA Prohibited List. The moment a UK seller or commentator makes a therapeutic claim, MHRA can treat the product as an unlicensed medicinal product.
Important: PeptideClear publishes encyclopedia commentary only and does not recommend human use. Speak to a UK-registered prescriber before any medical decision.
Related reading on PeptideClear
Encyclopedia entry
Retatrutide: what it is, animal evidence, regulatory framing
Editorial commentary on Retatrutide, including the literature base and UK availability framing.
UK regulatory record
Retatrutide: UK regulatory status
MoDA, PSA, MHRA, WADA and ASA positions for Retatrutide in plain English.
Frequently asked questions
What is the evidence level for Retatrutide?
What is the UK regulatory status of Retatrutide?
Has Retatrutide been tested in human clinical trials?
Where can I read the source literature for Retatrutide?
Last verified 2026-05-22. Editorial commentary, not legal or clinical advice. Citations without a linked identifier can be located through the PubMed search and the journal index.