What is retatrutide (reta peptide)?
9 min read · Updated September 2026 · MY PEPTIDES Research Team
Key facts
Retatrutide, development code LY3437943 and commonly shortened to "reta" or "reta peptide", is an investigational synthetic peptide described in the literature as a triple agonist: it activates the GLP-1, GIP and glucagon receptors together. That third target, the glucagon receptor, is what separates it from dual agonists such as tirzepatide and from single GLP-1 agonists such as semaglutide. It has been studied in published phase 2 clinical trials for obesity and for type 2 diabetes, run under medical supervision, and it remains investigational: it is not an approved medicine anywhere and has not been evaluated by the FDA. MY PEPTIDES does not sell retatrutide, so this page is educational only. It does not describe dosing or administration and makes no therapeutic claims. Readers researching the triple-agonist class often also look at established growth-hormone and metabolic research peptides, which we do supply to US laboratories, pre-mixed and with a batch Certificate of Analysis, and which our other guides cover in detail.
Retatrutide, which most people shorten to reta or reta peptide, has become one of the most searched compounds in the peptide world, and US interest has climbed steeply since 2024 as its clinical trial results were published. This page explains, in plain language, what retatrutide actually is, how it differs from the compounds it gets compared to, and what the research has and has not looked at. It is written for US readers trying to separate the underlying science from the marketing that surrounds the name.
Educational, research context only. Retatrutide is an investigational compound. It is not an approved medicine, it has not been evaluated by the FDA, and nothing here is medical advice or dosing guidance. MY PEPTIDES does not sell retatrutide. This page exists because a great many people are trying to understand the compound, and clear, honest information is hard to find.
What retatrutide is
Retatrutide is a synthetic peptide developed under the code LY3437943. In the literature it is described as a triple agonist, which means it activates three receptors rather than one:
- GLP-1 receptor (glucagon-like peptide-1)
- GIP receptor (glucose-dependent insulinotropic polypeptide)
- Glucagon receptor
The first two, GLP-1 and GIP, are incretin receptors that several well-known compounds already target. The third, the glucagon receptor, is the part that makes retatrutide distinct. Engaging the glucagon receptor alongside the two incretin receptors is the defining feature of the molecule, and it is why researchers treat retatrutide as its own compound rather than as a variation on an earlier drug.
The triple-agonist idea, briefly
Incretin receptors such as GLP-1 and GIP are involved in how the body handles glucose and appetite signaling. The glucagon receptor is involved in energy expenditure and in how the liver handles fuel. The hypothesis behind a triple agonist is that engaging all three at once produces a different metabolic profile than engaging one or two. Whether that hypothesis holds, and in what way, is exactly what clinical research on the compound has been testing. It is a hypothesis under investigation, not a settled result.
Retatrutide vs tirzepatide vs semaglutide
This is the comparison people search for most often. The simplest way to keep them straight is by how many receptors each one targets.
| Compound | Receptors targeted | Agonist type |
|---|---|---|
| Semaglutide | GLP-1 | Single |
| Tirzepatide | GLP-1 + GIP | Dual |
| Retatrutide | GLP-1 + GIP + glucagon | Triple |
So semaglutide is a single agonist, tirzepatide is a dual agonist, and retatrutide adds the glucagon receptor to become a triple agonist. They are not interchangeable, and in any serious comparison the glucagon-receptor activity is the variable that sets retatrutide apart.
What the published research actually examined
It is worth separating what the primary literature examined from what is claimed downstream, because searches for retatrutide return a great many confident benefit lists, and the distance between the two is large.
Retatrutide has been studied in phase 2 clinical trials, which are formal medical studies run under supervision, not laboratory bench work. Two are frequently cited:
- A phase 2 obesity trial published in the New England Journal of Medicine in 2023, which examined retatrutide in adults with obesity over 48 weeks.
- A phase 2 type 2 diabetes trial published in The Lancet in 2023, which examined it in adults with type 2 diabetes.
Both were early-stage trials. Phase 2 establishes preliminary signals and tolerability; it does not settle long-term outcomes or safety at scale, which is what later and larger phase 3 programs are designed to do. Much of what circulates online as "retatrutide results" extrapolates well beyond what these two phase 2 studies reported. Anyone citing retatrutide should be clear about which trial and which phase they are referring to, because the distinction changes what the number actually means.
What retatrutide is not
- It is not an approved medicine in the United States or anywhere else, and it has not been evaluated by the FDA.
- It is not a product we sell. Retatrutide is tied to an active clinical development program, and it is not part of our catalog.
- It is not the same as tirzepatide or semaglutide. The glucagon-receptor activity makes it a distinct compound, not a stronger version of the dual or single agonists.
- It is not a finished science. The published human data is phase 2, so treat firm claims about outcomes with caution.
Why we do not sell retatrutide
We will be direct, because it is the honest answer to a common question: MY PEPTIDES does not stock retatrutide. It is an investigational compound tied to an active clinical development program, and we do not carry it.
If you arrived here while researching the broader class, the peptides we do supply for laboratory research include established growth-hormone-axis and metabolic research compounds. Our tesamorelin guide covers a well-characterized GHRH analog, and our overview of what research peptides are is a good starting point for how this material is handled and verified. Every compound we supply ships with a batch Certificate of Analysis.
How the peptides we do supply reach US labs
Retatrutide is not one of them, but for the research compounds we do carry, here is how supply works for US laboratories, since it is the next question readers usually ask. Every compound is synthesized in our own UK laboratory rather than imported and repackaged, and each US batch is verified in a US laboratory before it ships. Orders leave as a pre-mixed solution rather than a lyophilized powder, prepared under controlled conditions and HPLC-verified, with a batch-specific Certificate of Analysis that reports HPLC for purity and mass spectrometry for identity. They are dispatched cold-chain from the warehouse that serves the United States, with tracked delivery across the country next business day, priced in US dollars and payable by Visa, Mastercard or Apple Pay. Store the vials refrigerated at 2-8°C on arrival, not frozen. None of this applies to retatrutide, which we do not supply; it describes the compounds in our catalog.
Regulatory status
Retatrutide is investigational. It is not approved as a medicine by any regulator, it has not been evaluated by the FDA, and any material described as retatrutide is not a licensed pharmaceutical. Approval, if it comes, follows the completion of phase 3 trials and regulatory review, and that process was ongoing at the time of writing. Treat any claim that retatrutide is an approved or available medicine with caution.
Dosing and administration
We do not publish dosing, reconstitution-for-use or administration guidance for retatrutide, and there is a second reason beyond our standard research-use policy: we do not supply the compound at all, and it is investigational, so quantity guidance aimed at a person would be inconsistent with both what is known and what is available. Experimental parameters in the published trials were set by the investigators under medical supervision and belong in the primary literature, not on a storefront.
Related reading
- What is tesamorelin? - a well-characterized GHRH analog we do supply.
- What are research peptides? - how this material is defined, handled and verified.
- What is a Certificate of Analysis? - how to read the document every compound we ship comes with.
Frequently asked questions
The short answers below mirror what the research actually supports.
Frequently asked questions
- What is reta peptide?
- "Reta peptide" is the common shorthand for retatrutide, an investigational synthetic peptide (development code LY3437943) described as a triple agonist of the GLP-1, GIP and glucagon receptors. It is not an approved medicine, it has not been evaluated by the FDA, and MY PEPTIDES does not sell it.
- What is the difference between retatrutide and tirzepatide?
- Tirzepatide is a dual agonist: it targets the GLP-1 and GIP receptors. Retatrutide is a triple agonist: it targets those two plus the glucagon receptor. That added glucagon-receptor activity is the defining difference between them, and it is why they are studied as distinct compounds rather than as versions of the same one.
- Is retatrutide FDA-approved?
- No. Retatrutide is investigational and has not been approved or evaluated by the FDA, or by any other regulator. It has been studied in phase 2 clinical trials for obesity and type 2 diabetes, but approval requires the completion of later-stage trials and regulatory review, which was still ongoing at the time of writing.
- Does MY PEPTIDES sell retatrutide, and how fast do your peptides ship in the US?
- We do not stock retatrutide; it is tied to an active clinical development program and is not part of our catalog, so this page is educational only. For the compounds we do supply for laboratory research, US orders ship cold-chain from the warehouse that serves the United States, with tracked delivery across the country next business day, priced in US dollars and payable by Visa, Mastercard or Apple Pay.
- What does the glucagon receptor add?
- The GLP-1 and GIP receptors are incretin receptors involved in glucose handling and appetite signaling. The glucagon receptor is involved in energy expenditure and hepatic fuel handling. Adding glucagon-receptor activity is the hypothesis behind a triple agonist, and it is what distinguishes retatrutide from dual agonists like tirzepatide.