The Definitive
Retatrutide Resource
Plain-English answers about LY3437943 — the first triple GIP/GLP-1/glucagon receptor agonist. Phase 3 trial results, how it works, side effects, and the latest 2026 research.
Independent and peer-reviewed. Also covers how the drug compares to Wegovy, Zepbound, CagriSema, and Foundayo. No product sales.
New to Retatrutide?
What Is Retatrutide?
Understand the basics of this investigational triple-agonist peptide and why it matters.
Read article 02Mechanism of Action
Learn how the drug activates GLP-1, GIP, and glucagon receptors at the same time.
Read article 03Safety Overview
Review the side effects, dose-by-dose adverse events, and tolerability data from clinical trials.
Read articlePhase 3 in 2026 at a Glance
Mean percent body weight reduction at the highest tested dose, efficacy estimand. Cross-trial comparison only — no head-to-head data are available between retatrutide and other agents.
Presented at ADA 2026 · June 6
TRIUMPH-1: 28.3% mean weight loss in 2,339 adults
Full TRIUMPH-1 data were presented at the American Diabetes Association 2026 Scientific Sessions, alongside the companion diabetes trial TRANSCEND-T2D-1, which was published the same day in The Lancet. Beyond the 28.3% mean weight loss at 12 mg, the nested comorbidity groups showed benefits well beyond the scale.
- 45.3% of 12 mg participants lost at least 30% of body weight
- 65.3% ended the trial with a BMI below 30
- -30.3% at 104 weeks in the BMI ≥35 subgroup
- -73.1% knee-pain and -60.6% sleep-apnea reductions (nested baskets)
Featured Knowledge
How to Get Retatrutide: Clinical Trials, Access, and Availability
Retatrutide is not approved as of 2026. Learn about clinical trial access, the TRIUMPH program, FDA approval timeline (2027-2028), and online safety risks.
Safety Profile of Retatrutide: Comprehensive Overview from Clinical Data
A thorough review of retatrutide's safety profile based on Phase 1, Phase 2, and Phase 3 TRIUMPH-4 clinical trial data, covering gastrointestinal adverse events, dysesthesia, laboratory findings, cardiovascular signals, hepatic effects, and outstanding safety questions.
What Is Retatrutide? A Comprehensive Overview of LY3437943
An in-depth introduction to retatrutide (LY3437943), the first-in-class triple GIP/GLP-1/glucagon receptor agonist in development by Eli Lilly for obesity and type 2 diabetes.
Explore Topics
Knowledge Base
In-depth articles on pharmacology, mechanism of action, safety, and outcomes.
Clinical Trials
Phase 2 and Phase 3 trial data, enrollment status, and key results.
Comparisons
Side-by-side analysis with semaglutide, tirzepatide, and other GLP-1 agonists.
Blog
Analysis, commentary, and updates on retatrutide research and development.
FAQ
Answers to the most common questions about retatrutide.
Glossary
Definitions of medical and scientific terms used across the knowledge base.
Trial Developments
TRIUMPH-1
TRIUMPH-1: Phase 3 Pivotal Obesity Trial of Retatrutide (Results-Published)
The pivotal Phase 3 obesity trial of retatrutide. Topline results announced May 21, 2026: 28.3% mean weight loss at 12 mg over 80 weeks (n=2,339 adults with obesity or overweight + at least one weight-related comorbidity, no diabetes). All three doses met primary and key secondary endpoints. The largest pivotal weight-loss readout in the retatrutide program to date.
Retatrutide Dose Escalation Optimization
Phase 3b Dosing Optimization Study for Retatrutide
Investigating different retatrutide dose escalation schemes to optimize efficacy-tolerability balance.
SYNERGY-OUTCOMES
SYNERGY-OUTCOMES Trial: Retatrutide for Liver Disease (MASH)
SYNERGY-OUTCOMES is a Phase 3 trial testing retatrutide and tirzepatide vs placebo to prevent major adverse liver outcomes in high-risk MASLD/MASH. What it studies.
Latest from the Blog
What Is MASH? Retatrutide's Liver-Disease Program Explained
How retatrutide targets MASH liver disease: the glucagon-driven liver-fat effect, plus what the SYNERGY-OUTCOMES and MACELD Phase 3 trials aim to prove.
How Was Retatrutide Discovered? The Triple-Agonist Story
Retatrutide was built by adding glucagon action to the GIP/GLP-1 backbone behind tirzepatide. Inside the discovery science of the first triple agonist.
How Fast Does Retatrutide Work? A Week-by-Week Timeline
A week-by-week and month-by-month look at retatrutide's trial-measured weight loss, mapped to the 2 mg-to-12 mg dose-escalation schedule.
When Was Retatrutide Created? Timeline 2016 to 2026
Retatrutide entered human trials in 2019, about 7 years ago. A year-by-year timeline from its 2016 design to 2026 Phase 3 data — still investigational.
Retatrutide at ADA 2026: TRIUMPH-1 and TRANSCEND-T2D-1 Deliver — and Get Published in The Lancet
At the ADA 2026 Scientific Sessions (June 6), retatrutide's pivotal TRIUMPH-1 obesity and TRANSCEND-T2D-1 diabetes results were presented in full — with TRANSCEND-T2D-1 published simultaneously in The Lancet. Beyond weight loss, nested baskets showed 73.1% knee-pain and 60.6% sleep-apnea reductions.
TRIUMPH-1 Phase 3 Results: Retatrutide Delivers 28.3% Weight Loss in 2,339-Patient Obesity Trial
Eli Lilly's pivotal TRIUMPH-1 Phase 3 trial of retatrutide (May 21, 2026) reported 28.3% mean weight loss at 12 mg over 80 weeks, with 45.3% of participants losing 30%+ of body weight. Full results, safety profile, and what it means for the regulatory timeline.