Retatrutide Clinical Trials: Phase 2 & Phase 3 Research Tracker
Retatrutide is an investigational GIP, GLP-1 and glucagon receptor agonist being studied in a large clinical development program. This tracker organizes published Phase 2 research, Phase 3 TRIUMPH and TRANSCEND studies, reported results and ongoing trials in one place.
What is the current status of Retatrutide clinical trials?
Retatrutide, also known by its development code LY3437943, is designed to activate three hormone receptors: glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1) and glucagon.
The clinical development program extends beyond a single obesity trial. Studies are evaluating Retatrutide across populations that include obesity or overweight, type 2 diabetes, cardiovascular disease, osteoarthritis-related outcomes, weight maintenance and other obesity-associated conditions.
This page separates published evidence, sponsor-announced topline results, and ongoing registered trials. Those categories should not be treated as interchangeable: peer-reviewed publication provides substantially more methodological detail than a topline announcement.
Retatrutide Phase 2 Trial
A randomized, double-blind, placebo-controlled Phase 2 trial evaluated Retatrutide in 338 adults with obesity or overweight plus at least one weight-related condition. Participants received different Retatrutide dose regimens or placebo for 48 weeks.
Study population
338 adults participated in the Phase 2 obesity trial.
Study duration
The trial evaluated weight change and other outcomes across a 48-week treatment period.
Peer-reviewed results
The results were published in the New England Journal of Medicine in 2023.
What did the Phase 2 obesity study report?
At 48 weeks, mean body-weight change was −8.7% in the 1 mg group, −17.1% across the combined 4 mg groups, −22.8% across the combined 8 mg groups and −24.2% in the 12 mg group, compared with −2.1% with placebo.
These findings helped establish the basis for the much larger Phase 3 clinical development program. Phase 2 findings, however, should not be treated as proof of regulatory approval or as a substitute for results from later-stage trials.
Retatrutide Phase 3 Clinical Trial Tracker
The Phase 3 program is substantially broader than one pivotal obesity study. The table below organizes several of the major registered or reported studies and the research question each is designed to address.
| Trial | Phase | Primary Population / Question | Status / Evidence | ClinicalTrials.gov ID |
|---|---|---|---|---|
| TRIUMPH-1 | Phase 3 | Obesity or overweight without diabetes; master protocol also included specific OA and OSA populations | Topline results reported in 2026 | NCT05929066 |
| TRIUMPH-2 | Phase 3 | Obesity or overweight with type 2 diabetes | Topline results reported in 2026 | Verify current registry record |
| TRIUMPH-3 | Phase 3 | Severe obesity and established cardiovascular disease | Topline results reported in 2026 | NCT05882045 |
| TRIUMPH-4 | Phase 3 | Obesity or overweight with knee osteoarthritis | Completed; topline results disclosed | NCT05931367 |
| TRIUMPH-5 | Phase 3 | Retatrutide compared with tirzepatide in adults with obesity | Phase 3 study | NCT06662383 |
| TRIUMPH-6 | Phase 3 | Maintenance of weight reduction in people with obesity | Active, not recruiting at last review | NCT06859268 |
| TRIUMPH-7 | Phase 3 | Obesity or overweight with chronic low back pain | Active, not recruiting at last review | NCT07035093 |
| TRIUMPH-8 | Phase 3b | Obesity or overweight without type 2 diabetes | Active, not recruiting at last review | NCT07232719 |
| TRIUMPH-9 | Phase 3 | Evaluation of different Retatrutide dose-escalation schemes | Enrollment completed according to sponsor trial information | NCT07357415 |
| TRANSCEND-T2D-1 | Phase 3 | Type 2 diabetes inadequately controlled with diet and exercise | Completed; Phase 3 results published | NCT06354660 |
What is the Retatrutide TRIUMPH program?
TRIUMPH-1
TRIUMPH-1 evaluated Retatrutide in adults with obesity or overweight and at least one weight-related comorbidity without diabetes. Lilly reported positive Phase 3 topline results in May 2026.
TRIUMPH-2
TRIUMPH-2 studied adults with obesity or overweight and type 2 diabetes. Lilly announced positive topline results in July 2026.
TRIUMPH-3
TRIUMPH-3 evaluated adults with severe obesity and established cardiovascular disease, with or without type 2 diabetes. The ClinicalTrials.gov record lists 1,946 actual participants and an April 2026 primary completion.
TRIUMPH-4
TRIUMPH-4 studied Retatrutide in participants with obesity or overweight and osteoarthritis of the knee. The ClinicalTrials.gov record lists the trial as completed.
TRIUMPH-5
TRIUMPH-5 is especially important for comparative research because it evaluates Retatrutide directly against tirzepatide in adults with obesity rather than comparing Retatrutide only with placebo.
TRIUMPH-6 through TRIUMPH-9
Later TRIUMPH studies expand the research program into questions including maintenance of weight reduction, chronic low back pain, additional obesity populations and different dose-escalation strategies.
What is the TRANSCEND Retatrutide program?
TRANSCEND focuses on the development of Retatrutide in type 2 diabetes. This program is distinct from, but complementary to, the obesity-focused TRIUMPH research program.
Additional TRANSCEND studies expand the type 2 diabetes program into different treatment backgrounds and patient populations. When interpreting these trials, it is important to distinguish completed studies with published results from trials that are still underway or have not yet produced peer-reviewed findings.
Retatrutide Clinical Research Timeline
Phase 2 obesity results published
The randomized Phase 2 obesity trial was published in the New England Journal of Medicine.
Phase 3 program expands
Multiple TRIUMPH trials begin evaluating obesity, cardiovascular disease, knee osteoarthritis and related research questions.
TRIUMPH-4 topline findings disclosed
Phase 3 results were announced from the knee osteoarthritis study.
TRANSCEND-T2D-1 reports Phase 3 results
Results from the type 2 diabetes program were reported and subsequently published.
TRIUMPH-1 results announced
Lilly reported positive topline Phase 3 obesity results.
TRIUMPH-2 and TRIUMPH-3 results announced
Lilly disclosed additional Phase 3 results covering obesity with type 2 diabetes and severe obesity with cardiovascular disease.
Additional Phase 3 research continues
Several registered studies continue to investigate additional populations, comparative effectiveness, weight maintenance and obesity-associated conditions.
Clinical Trial Evidence Is Not the Same as Peptide Sample Verification
This distinction is particularly important with an investigational molecule such as Retatrutide.
Clinical trials can evaluate
- Outcomes in defined study populations
- Safety observations under a controlled protocol
- Comparisons with placebo or another treatment
- Predefined clinical endpoints
- Results associated with the sponsor's investigational product
Clinical trials do not verify
- The identity of an unrelated commercial sample
- The purity of a vial purchased from a third party
- Whether a supplier's COA matches a specific batch
- The quantity contained in an independently sourced vial
- Whether third-party material is equivalent to Lilly's investigational product
What can independent analytical testing establish?
Independent laboratory testing addresses a different question: what does the submitted sample analytically contain?
HPLC can provide a chromatographic purity profile, while LC-MS can provide evidence supporting molecular identity. Other tests evaluate separate characteristics such as quantity, sterility, bacterial endotoxin or specified contaminants. No single analytical method establishes every quality characteristic.
Need independent peptide testing?
Review Peptide Validation's available laboratory testing services for independent sample analysis and batch-specific documentation.
Is Retatrutide FDA approved?
A successful clinical trial and regulatory approval are separate events. Phase 3 evidence may support a future regulatory submission, but regulators independently evaluate the submitted evidence before deciding whether a drug may be approved for a particular indication.
Likewise, an independently generated Certificate of Analysis does not make a Retatrutide sample FDA approved. Analytical testing evaluates characteristics of the submitted sample; it does not confer drug approval, establish clinical effectiveness or determine that a sample is appropriate for human administration.
Retatrutide Research: How to Interpret New Results
When a new Retatrutide result is announced, check what kind of evidence is actually available.
Trial registration
Shows the study design, population, endpoints, sponsor and status. Registration does not mean results are available.
Topline announcement
Provides an initial sponsor summary but generally contains less methodological and statistical detail than a full publication.
Peer-reviewed publication
Provides substantially more detail for evaluating study design, statistical methods, outcomes, limitations and adverse events.
Retatrutide Clinical Trials FAQ
What phase of clinical trials is Retatrutide in?
Retatrutide is in Phase 3 clinical development. Multiple Phase 3 studies have reported results, while additional Phase 3 trials remain part of the ongoing development program.
What is LY3437943?
LY3437943 is the development code for Retatrutide, an investigational agonist targeting the GIP, GLP-1 and glucagon receptors.
What was the Retatrutide Phase 2 trial?
The published Phase 2 obesity trial was a randomized, double-blind, placebo-controlled study involving 338 adults. It evaluated several Retatrutide dose regimens over 48 weeks.
What is the TRIUMPH Retatrutide program?
TRIUMPH is a Phase 3 clinical development program evaluating Retatrutide across obesity or overweight populations and several associated conditions. It includes multiple distinct trials rather than one single study.
What is TRANSCEND-T2D?
TRANSCEND-T2D is the Retatrutide Phase 3 development program focused on type 2 diabetes populations.
Has Retatrutide completed Phase 3 trials?
Yes. Several individual Phase 3 studies have completed or reported results, while other Phase 3 studies remain underway. The status of the overall development program should not be reduced to the status of one trial.
Is Retatrutide FDA approved?
No. As of August 24, 2026, Retatrutide remains investigational and has not been approved by the FDA. Clinical-trial results do not themselves constitute regulatory approval.
Is Retatrutide the same as a GLP-1 drug?
Retatrutide includes GLP-1 receptor agonism but also targets GIP and glucagon receptors. It is therefore more accurately described as a GIP, GLP-1 and glucagon receptor agonist rather than simply a GLP-1 agonist.
Can a Retatrutide clinical trial verify a commercial Retatrutide sample?
No. Clinical trials evaluate a sponsor's investigational product under a defined research protocol. They do not verify the identity, purity, quantity or batch documentation of an unrelated third-party sample labeled Retatrutide.
How can a Retatrutide sample be independently tested?
Independent analytical testing can evaluate a submitted sample using methods selected for the quality question being investigated. For example, HPLC can evaluate chromatographic purity while LC-MS can provide evidence supporting molecular identity. Separate methods are needed for other quality characteristics.
Where can I check whether a Retatrutide trial is recruiting?
ClinicalTrials.gov and the study sponsor's clinical-trial portal should be checked for current recruitment status, eligibility criteria and study locations because trial status can change over time.
Related Retatrutide & Peptide Testing Resources
Trial information should be cross-checked against ClinicalTrials.gov, peer-reviewed publications and sponsor disclosures because study status and reported findings may change as the development program progresses.