GLP-3 Retatrutide
Popular “GLP-3” nickname · GIP / GLP-1 / glucagon triple agonist
High-interest investigational triple agonist with substantial human trial evidence across obesity and metabolic research.
Reference dose
0.3–12 mg weekly
Source-specific educational reference, not an individualized recommendation.
Reference schedule
Weekly · 12–48 weeks
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This page gets detailed quickly.
Profiles include evidence, formats, units, source-specific reference amounts and, where relevant, device details. If any of those terms are unfamiliar, do not guess your way through them. Start with a Personalised Guide and we will put the foundations in the right order for you.
At a glance
Targets
GIP + GLP-1 + glucagon
Three metabolic receptor systems in one investigational molecule.
Clinical stage
Phase 3
Multiple pivotal trial topline results were reported in 2026.
Regulatory status
Not approved
No approved commercial retatrutide product exists as of September 2026.
Strongest evidence
Human randomized trials
Phase 2 is peer reviewed; phase 3 data are still partly sponsor-reported topline results.
What it is
Retatrutide is an investigational peptide-based drug developed by Eli Lilly that activates the GIP, GLP-1 and glucagon receptors.
It is being developed as a once-weekly injectable medicine for obesity and related cardiometabolic conditions, but it has not yet received regulatory approval.
Research focus
How it works
Retatrutide is designed to activate GIP, GLP-1 and glucagon receptors, combining appetite, glycaemic and energy-balance signalling in one investigational molecule.
Important context
GLP-3 Retatrutide is one of the most closely watched peptide-based metabolic research programmes, with peer-reviewed phase 2 evidence and multiple positive phase 3 results. “GLP-3” is a popular informal nickname for the three-receptor design; scientifically, retatrutide targets GIP, GLP-1 and glucagon receptors rather than a receptor called GLP-3.
What it is studied for
Obesity research focuses on whether simultaneous activation of three metabolic pathways can produce larger or broader effects than single- or dual-receptor agonism.
Type 2 diabetes trials evaluate glycaemic control alongside weight and other metabolic outcomes.
Later-stage programmes also examine obesity complications such as cardiovascular disease, knee osteoarthritis pain and obstructive sleep apnoea.
More contextHow to read the retatrutide evidenceSee the deeper context, evidence details and practical distinctions behind this profile.
The strongest published evidence comes from defined clinical-trial populations using staged dose escalation and manufactured study drug. Those results should not be converted into a universal body-weight dosing formula.
In 2026 Lilly reported positive phase 3 topline results across several TRIUMPH studies. Sponsor-reported topline results are important, but they are not the same evidentiary layer as a complete peer-reviewed publication or an approved prescribing label.
- The 2023 phase 2 obesity trial enrolled adults with obesity or overweight plus a weight-related condition and without diabetes.
- At 48 weeks, higher-dose phase 2 groups showed large mean weight reductions, with gastrointestinal adverse events and a dose-related heart-rate increase among the notable safety findings.
- In May and July 2026 Lilly announced positive phase 3 obesity results, including trials in people with and without type 2 diabetes and people with established cardiovascular disease.
- Lilly continues to state that retatrutide is investigational and has warned against products sold outside its clinical trials.
Why people are interested
What makes GLP-3 Retatrutide worth researching.
Phase 2 published + phase 3 topline
Weight reduction
Randomized phase 2 data showed substantial dose-related weight reduction over 48 weeks, and Lilly later reported larger phase 3 reductions over longer treatment periods.
Human clinical trials
Metabolic effects
Clinical development has shown improvements in glycaemic measures as well as body weight, including in people with type 2 diabetes.
Clinical pharmacology
Triple-agonist mechanism
Retatrutide combines incretin signalling through GIP and GLP-1 receptors with glucagon-receptor activity, differentiating it mechanistically from single- and dual-receptor drugs.
Human clinical trials
Safety remains part of the story
Gastrointestinal adverse events have been common in trials, and phase 2 showed a dose-related rise in heart rate that later declined.
Evidence
Where the evidence is strongest, and what kind of evidence it is.
Human · randomized · peer reviewed
Phase 2 obesity trial
The 48-week trial demonstrated a clear dose-response for body-weight reduction in adults with obesity or overweight plus a weight-related condition.
Human · pivotal · topline
Phase 3 obesity programme
Lilly reported positive 2026 results across TRIUMPH studies, including populations with obesity, type 2 diabetes and established cardiovascular disease.
Human clinical trials
Adverse events
Gastrointestinal events are prominent and dose-related. Heart-rate increases were observed in phase 2, reinforcing that efficacy should not be separated from safety and titration.
Not clinical-trial equivalents
Products sold online
Lilly states that retatrutide is not approved and warns that products claiming to contain it outside Lilly-sponsored trials may have unknown composition, strength or contaminants.
Human research
A peer-reviewed 2023 phase 2 randomized trial in adults with obesity or overweight showed substantial dose-related weight reduction at 48 weeks. Gastrointestinal events were the most common adverse events, and heart rate increased in a dose-dependent pattern before declining later.
In 2026 Lilly announced positive pivotal phase 3 topline results from TRIUMPH-1, TRIUMPH-2 and TRIUMPH-3 across adults with obesity or overweight, including populations with type 2 diabetes and established cardiovascular disease.
The 2026 phase 3 announcements are sponsor-reported topline results. Full peer-reviewed publications and regulatory review remain important next evidence steps.
Preclinical research
Preclinical work supported the multi-receptor design and informed clinical development, but the current relevance of retatrutide is driven primarily by its human trial programme rather than animal efficacy claims.
Reference dosing
Reference amount, schedule and conversion.
A reference amount is only useful when you know the formulation, concentration and delivery device it belongs to. Do not transfer a vial amount into a pen, a pen click count into another pen, or a syringe-unit number into a different concentration.
01
Identify the format
Vial, reusable cartridge pen, prefilled multi-dose pen or single-dose autoinjector.
02
Confirm concentration
Know the total peptide amount and liquid volume or the manufacturer/vendor concentration.
03
Understand the units
Keep mg/mcg, mL and syringe units or device clicks separate.
04
Then use the reference
Only convert a known reference amount with the calculator that matches the actual device.
Source-specific reference
0.3–12 mg weekly
Weekly · 12–48 weeks
The 0.3–12 mg range reflects doses explored in clinical development. Trials used staged escalation and defined populations; the range is research context rather than an individualized schedule.
Calculator connection
Choose the calculator that matches the actual formulation. The calculator converts numbers you already know; it does not choose the target amount.
A research vial concentration only tells you how much drug is present per unit of liquid. It does not reproduce the manufacturing, device, titration or clinical oversight used in Lilly trials.
Storage
Start with the format. Then verify the exact product.
Rule of thumb, not a product instruction
Rule of thumb only: retatrutide remains investigational and has no approved consumer storage label. A third-party vial or pen should not be assumed to match the investigational product used in Lilly-sponsored trials.
Pen rule of thumb
For any premixed retatrutide research pen, use only product-specific storage information backed by the supplier's stability documentation. There is no approved retatrutide pen standard to borrow from.
Vial rule of thumb
For a retatrutide research vial, keep dry and reconstituted states separate and avoid inventing a generic refrigerator window. The exact formulation, diluent and container determine the storage question.
Known data
For retatrutide, the strongest storage fact is that there is no FDA-approved consumer product with validated public storage instructions. FDA states that retatrutide is not a component of an approved drug and has not been found safe and effective for any condition.
For retatrutide, clinical-trial material is manufactured and handled under sponsor-controlled study procedures. Those trial controls establish the integrity of the investigational product used in the programme, not a general storage standard for products sold online under the same name.
Formulation context
For retatrutide, formulation context matters because a clinical-trial product and a third-party research vial can differ in peptide identity, purity, excipients, concentration, lyophilization process, residual moisture, sterility and container closure.
For retatrutide, the molecule's investigational name does not establish that two products have the same stability or that a seller's vial is equivalent to Lilly's trial material.
What is not established
For retatrutide, what remains unestablished is a validated public post-reconstitution lifetime, standard diluent, freeze-thaw limit, room-temperature window or in-use storage period for third-party products.
For retatrutide, vendor storage instructions should therefore be presented as product-specific claims, ideally supported by analytical stability data, rather than as universal retatrutide rules.
Sources
The sources below support the product-specific storage distinctions above.
Practical reference
Formats
Injection in clinical trials
Reconstitution & units
Clinical trials use manufactured study drug and protocol-defined dosing. A research vial is not automatically equivalent to the investigational product used in those trials.
Trial doses are reported in mg. mL and syringe units describe liquid volume only when a specific concentration is known.
A calculator can convert a known concentration, but it cannot recreate a clinical-trial titration protocol or verify product identity.
Safety, status & open questionsOpen the practical cautionsGLP-3 Retatrutide has an advanced and highly promising human research programme. It remains investigational while full publication, regulatory review and potential commercial approval continue.
Open questions
Retatrutide remains investigational, so there is no approved label defining final indications, contraindications, commercial strengths or routine prescribing instructions.
Some phase 3 information available in 2026 is topline sponsor reporting rather than full peer-reviewed publication.
Clinical-trial product quality and titration protocols cannot be assumed for products marketed online as retatrutide.
Regulatory notes
Retatrutide has not been approved by FDA or any other regulatory agency as of September 2026.
Lilly has stated that products claiming to be retatrutide outside Lilly-sponsored clinical trials are not approved products and may have unknown composition or quality.
Lilly has said it plans regulatory submissions after completion of its pivotal programme; approval decisions remain with regulators.
Practical notes
Gastrointestinal adverse events such as nausea, vomiting and diarrhoea have been common in clinical development.
Phase 2 data showed dose-related increases in heart rate that peaked during treatment and later declined.
The safety profile is still being defined because retatrutide remains investigational and regulatory review is incomplete.
Products sold outside the clinical programme add independent risks around identity, purity, concentration and contamination.
Common mistakes
Calling retatrutide an approved weight-loss drug because phase 3 trials were positive.
Treating sponsor-reported topline results as if they were already an approved prescribing label.
Assuming the broad 0.3–12 mg clinical-development range is a universal titration schedule.
Assuming an online vial or pen is the same formulation used in Lilly clinical trials.
Common questions
Is retatrutide approved?
No. As of September 2026 it remains investigational despite positive phase 3 results.
How is retatrutide different from semaglutide?
Semaglutide is a GLP-1 receptor agonist with approved products. Retatrutide is an investigational triple agonist that targets GIP, GLP-1 and glucagon receptors.
Are phase 3 results available?
Yes. Lilly reported positive topline results from multiple phase 3 TRIUMPH trials in 2026. Some of those data have not yet completed the full peer-reviewed publication and regulatory-review process.
Does the trial dose range tell me what dose a person should use?
No. Clinical trials use protocol-defined eligibility, staged escalation and monitoring. The published range is evidence context, not an individualized dosing algorithm.
Related peptides & blends
References
Retatrutide for obesity — phase 2 trial
New England Journal of Medicine · 2023
Lilly — TRIUMPH-1 phase 3 topline results
Eli Lilly and Company · 2026
Lilly — TRIUMPH-2 and TRIUMPH-3 phase 3 topline results
Eli Lilly and Company · 2026
Lilly — what to know about retatrutide
Eli Lilly and Company · 2026
Retatrutide in type 2 diabetes — Phase 2
The Lancet / PubMed · 2023