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Medicine Retatrutide

An apothecary's notebook on retatrutide pharmacokinetics — what the published trials actually measured.

Where the medical facts came from

Retatrutide Study Sources and Links

Each entry explains its Phase 1/2/3 study or review. The full paper details follow.

Study results

Human studies behind the main findings

Each number matches a source used on this site. DOI means a permanent code for a paper. PubMed is a government library of medical papers. Retatrutide references appear below.

[1] Jastreboff AM, et al. This paper tested retatrutide for obesity in a Phase 2 study. N Engl J Med. 2023;389(6):514–526. paper code: 10.1056/NEJMoa2301972. https://pubmed.ncbi.nlm.nih.gov/37366315/

[2] Rosenstock J, et al. This Phase 2 study involved people with type 2 diabetes. It compared retatrutide with a placebo, which is a sugar pill, and another drug. Neither the people nor doctors knew each person’s group during the test. GLP-1 is one gut hormone the drug acts like. Lancet. 2023;402(10401):529–544. paper code: 10.1016/S0140-6736(23)01053-X. https://pubmed.ncbi.nlm.nih.gov/37385280/

[3] Li W, Zhou Q, Cong Z, et al. This lab paper used close pictures to show where retatrutide attaches to cells. The paper calls one of those places GLP-1R. Cell Discovery. 2024;10:77. paper code: 10.1038/s41421-024-00700-0. https://pmc.ncbi.nlm.nih.gov/articles/PMC11255275/

[4] Urva S, Coskun T, Loh MT, et al. LY3437943 is retatrutide’s early research name. Phase 1b means a small early test in people. This study used rising amounts in people with type 2 diabetes. Some got a placebo. Neither they nor the doctors knew who got which one. GLP-1 is one gut hormone involved. Lancet. 2022;400:1869–1881. paper code: 10.1016/S0140-6736(22)02033-5. https://pubmed.ncbi.nlm.nih.gov/36354040/

[5] Sanyal AJ, Kaplan LM, Frias JP, et al. Phase 2a means an early test of health results. This study involved people with fatty liver. People were placed by chance into the study groups. Nature Medicine. 2024;30:2037–2048. paper code: 10.1038/s41591-024-03018-2. https://pmc.ncbi.nlm.nih.gov/articles/PMC11271400/

[6] Katsi V, Koutsopoulos G, Fragoulis C, et al. This review weighs the early evidence for retatrutide as an obesity drug. Biomolecules. 2025;15:796. paper code: 10.3390/biom15060796. https://pmc.ncbi.nlm.nih.gov/articles/PMC12190491/

[7] Eli Lilly and Company. This early study tested LY3437943 in healthy adults. ClinicalTrials.gov. NCT04143802. 2019. https://clinicaltrials.gov/study/NCT04143802

Reviews explain risks and compare the studies

[8] Drucker DJ, et al. This review weighs how well GLP-1 medicines work for type 2 diabetes and obesity, along with their risks. This hormone comes from the gut. Diabetes Care. 2024;47(11):1873–1888. paper code: 10.2337/dci24-0003. https://doi.org/10.2337/dci24-0003

[9] Urva S, et al. This paper found that retatrutide slowed the movement of food out of the stomach. The drug acts like GLP-1 and two other hormones. Diabetes, Obesity & Metabolism. 2023;25(9):2784–2788. paper code: 10.1111/dom.15167. https://doi.org/10.1111/dom.15167

[10] Bailey CJ, et al. This review covers drugs that act like more than one gut hormone. It asks how they might help type 2 diabetes, obesity, and related illnesses. Peptides. 2025;187:171380. paper code: 10.1016/j.peptides.2025.171380. https://doi.org/10.1016/j.peptides.2025.171380

[11] Kokkorakis M, et al. This review compares obesity drugs that were still being studied. Pharmacological Reviews. 2025;77(1):100002. paper code: 10.1124/pharmrev.123.001045. https://doi.org/10.1124/pharmrev.123.001045

[12] Madsbad S, et al. This review compares short and long-lasting obesity drugs that act like a gut hormone. The paper uses GLP-1RA as its short name and covers phase 2 and 3 work. Expert Opinion on Investigational Drugs. 2025. paper code: 10.1080/13543784.2025.2472408. https://doi.org/10.1080/13543784.2025.2472408

[13] Laroche ML, et al. This review searched past reports for burning, tingling, or numb skin with drugs that act like GLP-1. GLP-1 is a gut hormone. European Journal of Clinical Pharmacology. 2026. paper code: 10.1007/s00228-026-04079-7. https://doi.org/10.1007/s00228-026-04079-7

[14] This smaller part of a 2025 type 2 diabetes study asked whether people lost muscle and fat while taking retatrutide. It appeared in Lancet Diabetes & Endocrinology. https://www.thelancet.com/journals/landia/article/PIIS2213-8587(25)00092-0/abstract

[15] Panou T, et al. This 2026 paper gives an overview of retatrutide studies in people with type 2 diabetes and obesity. Expert Review of Clinical Pharmacology. paper code: 10.1080/17512433.2026.2642415. https://doi.org/10.1080/17512433.2026.2642415

Reviews explain risks and compare the studies
  1. Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med. 2023;389(6):514–526. ↗
  2. Rosenstock J, et al. 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. Lancet. 2023;402(10401):529–544. ↗
  3. Li W, Zhou Q, Cong Z, et al. Structural insights into the triple agonism at GLP-1R, GIPR and GCGR manifested by retatrutide. Cell Discovery. 2024;10:77. ↗
  4. Urva S, Coskun T, Loh MT, et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial. Lancet. 2022;400:1869–1881. ↗
  5. Sanyal AJ, Kaplan LM, Frias JP, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nature Medicine. 2024;30:2037–2048. ↗
  6. Katsi V, Koutsopoulos G, Fragoulis C, et al. Retatrutide — A Game Changer in Obesity Pharmacotherapy. Biomolecules. 2025;15:796. ↗
  7. Eli Lilly and Company. A Study of LY3437943 in Healthy Participants. ClinicalTrials.gov. NCT04143802. 2019. ↗
  8. Drucker DJ, et al. Efficacy and Safety of GLP-1 Medicines for Type 2 Diabetes and Obesity. Diabetes Care. 2024;47(11):1873–1888. ↗
  9. Urva S, et al. The novel GIP, GLP-1 and glucagon receptor agonist retatrutide delays gastric emptying. Diabetes, Obesity & Metabolism. 2023;25(9):2784–2788. ↗
  10. Bailey CJ, et al. Multifunctional incretin peptides in therapies for type 2 diabetes, obesity and associated co-morbidities. Peptides. 2025;187:171380. ↗
  11. Kokkorakis M, et al. Emerging pharmacotherapies for obesity: A systematic review. Pharmacological Reviews. 2025;77(1):100002. ↗
  12. Madsbad S, et al. The promise of glucagon-like peptide 1 receptor agonists (GLP-1RA) for the treatment of obesity: a look at phase 2 and 3 pipelines. Expert Opinion on Investigational Drugs. 2025. ↗
  13. Laroche ML, et al. Dysesthesia associated with GLP-1 agonist therapies: data-mining analysis and literature review. European Journal of Clinical Pharmacology. 2026. ↗
  14. Body-composition substudy — retatrutide in type 2 diabetes: lean and fat mass outcomes. Lancet Diabetes & Endocrinology. 2025. ↗
  15. Panou T, et al. Retatrutide in type 2 diabetes mellitus and obesity: an overview. Expert Review of Clinical Pharmacology. 2026. ↗