Weight · Metabolism

Retatrutide

Peptilex evidence grade ABCDEUpdated 19 Oct 2026 How grades work

Type: Triple GIP, GLP-1 and glucagon receptor agonist
Main use or focus: Obesity; type 2 diabetes; related conditions (investigational)
Also known as: Reta, LY3437943

Key results

Retatrutide: average weight loss% of body weight lost on average

RetatrutidePlacebo

TRIUMPH-1¹80 wk · 2,339 participants

25.0%

3.9%

Phase 2¹48 wk · 338 participants

24.2%

2.1%

TRIUMPH-2¹80 wk · 1,152 participants · with type 2 diabetes

18.8%

5.1%

¹ Highest-level treatment group. Different trials, durations and populations – not a head-to-head comparison.

Sources: TRIUMPH-1 · NEJM 2026 · Phase 2 · NEJM 2023 · TRIUMPH-2 · Lancet 2026

Trial	Retatrutide	Comparison
TRIUMPH-1	25.0%	3.9%
Phase 2	24.2%	2.1%
TRIUMPH-2	18.8%	5.1%

10,000

people in the heart and kidney outcomes trial that is now running

Registered trialPhase 3Outcomes trial

Where it stands

Phase 3 is delivering: in TRIUMPH-1 (NEJM, 2026) adults with obesity lost 25% of their body weight on average over 80 weeks in the highest-level group, versus about 4% on placebo. A 10,000-person heart and kidney outcomes trial is running, and the manufacturer plans to file for approval in 2027.

How it works

How the new weight-loss medicines workWhich hormone receptors each one activates

	GLP-1	GIP	Glucagon	Amylin
Liraglutide1×
Semaglutide1×
Tirzepatide2×
Retatrutide3×
CagriSema2×

Source: Peptilex 1, profile overview (type of each peptide)

Go deeper

Full profile in the book

What it is, how it acts, the key studies, risks and open questions.

Peptilex – The Peptide Encyclopedia

34 peptides – from semaglutide to BPC-157 – in one book
An evidence grade (A–E) and the key studies for every peptide
Where each one stands in 2026 – US, EU and Switzerland

View on Amazon

Formats: Kindle · Paperback · Hardcover

Amazon store: amazon.com · Change store

Coming soonPeptilex – The Honest GLP-1 HandbookSemaglutide, tirzepatide and the new pills, explained for adults over 50.

Research at a glance

Publications by typePubMed, all years

All papers207

Human studies125

Animal studies only10

Randomized trials10

Meta-analyses & systematic reviews22

Source: PubMed and ClinicalTrials.gov via the Peptilex study database

Registered trials by phaseClinicalTrials.gov · name in study title

ongoing / startingcompleted / other

Phase 115

Phase 23

Phase 313

Other1

Source: PubMed and ClinicalTrials.gov via the Peptilex study database

Trial starts per yearClinicalTrials.gov · by start date (planned starts included)

2020

32022

62024

12026

Source: PubMed and ClinicalTrials.gov via the Peptilex study database

Registered trials

ClinicalTrials.gov · name in study title · ongoing first

Study	Phase	Status	Participants	Start
The Effect of Retatrutide Once Weekly on Cardiovascular Outcomes and Kidney Outcomes in Adults Living With Obesity (TRIUMPH-Outcomes) NCT06383390Eli Lilly and Company	Phase 3	Running	10,000	Apr 2024
Effect of Retatrutide Compared With Semaglutide in Adult Participants With Type 2 Diabetes and Inadequate Glycemic Control With Metformin With or Without SGLT2 Inhibitor (TRANSCEND-T2D-2) NCT06260722Eli Lilly and Company	Phase 3	Running	1,250	Feb 2024
A Study of Retatrutide (LY3437943) Compared to Tirzepatide (LY3298176) in Adults Who Have Obesity NCT06662383Eli Lilly and Company	Phase 3	Running	800	Nov 2024
A Study of Retatrutide (LY3437943) in the Maintenance of Weight Reduction in Individuals With Obesity NCT06859268Eli Lilly and Company	Phase 3	Running	643	Mar 2025
A Study of Retatrutide (LY3437943) in Participants Without Type 2 Diabetes Who Have Obesity or Overweight NCT07357415Eli Lilly and Company	Phase 3	Running	600	Jan 2026
A Study of Retatrutide (LY3437943) in Participants Who Have Obesity or Overweight and Chronic Low Back Pain NCT07035093Eli Lilly and Company	Phase 3	Running	586	May 2025
Effect of Retatrutide Compared With Placebo in Participants With Type 2 Diabetes and Moderate or Severe Renal Impairment, With Inadequate Glycemic Control on Basal Insulin, With or Without Metformin and/or SGLT2 Inhibitor (TRANSCEND-T2D-3) NCT06297603Eli Lilly and Company	Phase 3	Running	320	Mar 2024
A Study of Retatrutide (LY3437943) in Participants With Obesity or Overweight NCT07232719Eli Lilly and Company	Phase 3	Running	250	Nov 2025
A Study to Evaluate the Effect of Retatrutide on Insulin Secretion and Insulin Sensitivity in Adult Participants With Type 2 Diabetes Mellitus NCT06982859Eli Lilly and Company	Phase 1	Running	95	Jun 2025
Pre-approval Expanded Access of Retatrutide (LY3437943) NCT07629401Eli Lilly and Company	Expanded access	Expanded access	–	–

Show 15 moreShow fewer

Study	Phase	Status	Participants	Start
A Study of Retatrutide (LY3437943) in Participants Who Have Obesity or Overweight NCT05929066Eli Lilly and Company	Phase 3	Completed	2,335	Jul 2023
A Study of Retatrutide (LY3437943) in Participants With Obesity and Cardiovascular Disease NCT05882045Eli Lilly and Company	Phase 3	Completed	1,946	May 2023
A Study of Retatrutide (LY3437943) in Participants With Type 2 Diabetes Mellitus Who Have Obesity or Overweight NCT05929079Eli Lilly and Company	Phase 3	Completed	1,152	Jul 2023
Effect of Retatrutide Compared With Placebo in Adult Participants With Type 2 Diabetes and Inadequate Glycemic Control With Diet and Exercise Alone (TRANSCEND-T2D-1) NCT06354660Eli Lilly and Company	Phase 3	Completed	537	Apr 2024
A Study of Retatrutide (LY3437943) Once Weekly in Participants Who Have Obesity or Overweight and Osteoarthritis of the Knee NCT05931367Eli Lilly and Company	Phase 3	Completed	445	Aug 2023
A Study of LY3437943 in Participants Who Have Obesity or Are Overweight NCT04881760Eli Lilly and Company	Phase 2	Completed	338	May 2021
A Study of LY3437943 in Participants With Type 2 Diabetes NCT04867785Eli Lilly and Company	Phase 2	Completed	281	May 2021
A Study of Retatrutide (LY3437943) on Renal Function in Participants With Overweight or Obesity and Chronic Kidney Disease With or Without Type 2 Diabetes NCT05936151Eli Lilly and Company	Phase 2	Completed	146	Jul 2023
A Study to Measure Calorie Consumption and Usage in Participants With Obesity Using LY3437943 NCT06313528Eli Lilly and Company	Phase 1	Completed	85	Mar 2024
A Study of LY3437943 in Healthy Participants With a High Body Mass Index NCT05959096Eli Lilly and Company	Phase 1	Completed	85	Jul 2023
A Study to Investigate the Response of Participants With Type 2 Diabetes Mellitus on Once-Weekly Retatrutide to Hypoglycemia NCT06982846Eli Lilly and Company	Phase 1	Completed	80	Jun 2025
A Study of LY3437943 in Participants With Type 2 Diabetes Mellitus (T2DM) NCT04143802Eli Lilly and Company	Phase 1	Completed	72	Dec 2019
A Study of LY3437943 in Japanese Participants With Type 2 Diabetes Mellitus (T2DM) NCT04823208Eli Lilly and Company	Phase 1	Completed	64	May 2021
A Research Study Looking at Similarity Between LY3437943 Versions for Different Injection Devices NCT06003465Eli Lilly and Company	Phase 1	Completed	57	Aug 2023
A Study of LY3437943 in Postmenopausal Female Participants Who Are Overweight or Obese NCT06039826Eli Lilly and Company	Phase 1	Completed	46	Sep 2023

1 further registry entry from a sponsor we could not verify is not listed.

Showing 25 of 32 matching registered studies. See all on ClinicalTrials.gov.

Latest key papers

PubMed · newest first

2026
UBT251, a novel triple GLP-1, GIP, and glucagon receptor agonist, in adults with overweight or obesity: A multicenter, randomized phase 2 trial
Human RCTPhase 2Zhou Z et al. · Cell MetabolismPMID 42843337
2026
Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity
Human RCTPhase 3Jastreboff AM et al. · NEJMPMID 42814954
2026
Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial
Human RCTPhase 3Bellido V et al. · The LancetPMID 42810372
2026
Retatrutide-Associated Improvements in Cardiovascular Risk Biomarkers in Adults With Obesity With or Without Type 2 Diabetes
Human RCTPhase 2Ruotolo G et al. · Diabetes, Obesity & MetabolismPMID 42608321
2026
Comparative effects of drugs for adults with overweight or obesity: systematic review and network meta-analysis
Meta-analysisNong K et al. · BMJPMID 42419792
2026
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
Human RCTPhase 3Bajaj HS et al. · The LancetPMID 42250575
2026
Retatrutide and lipid and metabolite profiles in participants with obesity with or without type 2 diabetes
Human RCTPhase 2Pearson MJ et al. · J Clin Endocrinol MetabPMID 42135195
2025
Appetite, eating attitudes, and eating behaviours during treatment with retatrutide in adults with type 2 diabetes: Results of a phase 2 study
Human RCTPhase 2Kanu C et al. · Diabetes, Obesity & MetabolismPMID 40916752

In the research news

Related peptides

ASemaglutide ATirzepatide BCagriSema (cagrilintide)ALiraglutide APramlintide ASetmelanotide CAOD-9604