- What it is: A synthetic peptide (also called LY3437943) that acts at three hormone receptors at once: GLP-1, GIP and glucagon.
- Research areas: Body weight in obesity, blood sugar (HbA1c) in type 2 diabetes, and liver fat.
- Evidence level: Published human trials from phase 1 through phase 3, plus cell and mouse work. Still investigational, with no approval anywhere.
- The short version: Retatrutide is one of the newest metabolic compounds, and it already has real human trial data. Researchers recorded drops in body weight, blood sugar and liver fat within specific patient groups over less than a year. The trials logged mostly gut-related side effects, and none of this is a safety conclusion.
What it is
Retatrutide is a synthetic peptide of 39 amino acids with a fatty-acid chain attached partway along it. It is a single molecule that acts at three receptors: GLP-1, GIP and glucagon. In trials it goes by its generic name, retatrutide, or its development code, LY3437943.
Specs at a glance. Reference values for the compound named on the label, from PubChem or KEGG. They describe the compound, not a measurement of the vial you receive. Molecular weight is the free base (the peptide alone, without a salt). Synthetic peptides are usually supplied as a salt such as acetate or TFA, and the salt in this vial has not been confirmed.
| Compound | Retatrutide |
|---|---|
| Sequence | Y-Aib-QGTFTSDYSI-aMeL-LDKKAQ-Aib-AFIEYLLEGGPSSGAPPPS-NH2 (39 aa), C20 diacid on Lys17 via gamma-Glu + AEEA |
| Molecular formula | C221H342N46O68 |
| Molecular weight | 4731.34 g/mol (average, free base) |
| CAS number | 2381089-83-2 |
| Reference record | KEGG D12430 |
| Form | Lyophilized (freeze-dried) powder in one sealed vial |
| Vial sizes | 10 mg or 30 mg per vial |
| Storage (dry powder) | -20°C or colder, long term. Keep the vial sealed and away from light. |
| Lab report | Janoshik Analytical, October 2025 and May 2026. Ordered by the supplier, not by Etched Research. The report carries no lot number, so it is not matched to the vial you receive. Results on this page ↓ · All lab reports → |
What the evidence is
Retatrutide has been given to people in phase 1, phase 2 and phase 3 trials, all in adults with obesity or overweight, type 2 diabetes, or fatty liver disease. Behind them sit cell and mouse studies from its developers.
| Study | Type | Who or what | What was given | What it measured | What it found |
|---|---|---|---|---|---|
| Coskun et al., Cell Metabolism, 2022 | Cell, animal, and human phase 1 | Receptor tests in cells, mice with obesity, and a single-dose phase 1 study in people | Single rising doses in the phase 1 study | Receptor activity, body weight and blood sugar in mice, safety and blood levels in people | Active at all three receptors in cells. Body weight fell in mice. In people, its blood-level profile supported a once-weekly schedule, and body weight was still lower 43 days after one dose |
| Jastreboff et al., New England Journal of Medicine, 2023 | Human, phase 2, randomized, double-blind, placebo-controlled | 338 adults with obesity, or overweight plus a weight-related condition | 1 to 12 mg once a week, 48 weeks | Change in body weight | Average body weight fell in every retatrutide group, more at higher doses, with little change on placebo. Gut side effects were the most common and rose with dose. Heart rate rose with dose, peaked at 24 weeks, then eased |
| Rosenstock et al., Lancet, 2023 | Human, phase 2, randomized, double-blind, placebo- and active-controlled | 281 adults with type 2 diabetes | 0.5 to 12 mg once a week, 36 weeks | HbA1c (a long-term blood sugar marker), then body weight | HbA1c fell more than placebo at 4 mg and above, and more than the active comparator drug in two of the higher-dose groups. Body weight fell with dose. Gut side effects were mostly mild to moderate |
| Sanyal et al., Nature Medicine, 2024 | Human, phase 2a substudy, randomized, placebo-controlled | 98 adults from the obesity trial above who had fatty liver disease | 1, 4, 8 or 12 mg once a week | Change in liver fat at 24 weeks | Liver fat fell at every dose, with almost no change on placebo. Most people in the two highest-dose groups reached a normal liver-fat level |
| Bajaj et al. (TRANSCEND-T2D-1), Lancet, 2026 | Human, phase 3, randomized, double-blind, placebo-controlled | 537 adults with type 2 diabetes managed by diet and exercise alone | 4, 9 or 12 mg once a week, 40 weeks | HbA1c, then body weight | HbA1c and body weight fell more than placebo at all three doses. Gut side effects were the most common, mostly mild to moderate, and eased over time |
Last reviewed 2026-09-24. Every trial above was funded by the developer. The numbers behind each row, and what none of it establishes, are on the full research summary →
Lab reference
Janoshik Analytical has tested retatrutide from supplier stock three times. Each result covers only the size named.
- 10mg, tested 23 October 2025. Two vials measured 99.419% and 99.477% purity, and 10.61 mg and 10.37 mg of peptide against the 10 mg label.
- 30mg, tested 24 October 2025. Two vials measured 99.393% and 99.764% purity, and 30.61 mg and 29.11 mg of peptide against the 30 mg label.
- 30mg, tested 4 May 2026. One vial measured 99.777% purity and 32.79 mg of peptide against the 30 mg label.
See them on the lab reference page →
What those reports do not cover: they are reference tests of the compound from supplier stock, not tests of the vial in your order. The 10mg size has one dated report and the 30mg size has two. None of them tested for endotoxin, sterility or heavy metals.
Storage and shipping
Ships as lyophilized powder in a sealed vial. Store the powder frozen at -20°C. US addresses only. Shipping costs and cutoff times →
Questions about Retatrutide
What is Retatrutide?
Retatrutide (development code LY3437943) is a synthetic peptide that acts at three hormone receptors at once: GLP-1, GIP and glucagon. Its research runs from cell and mouse work to human trials (Coskun et al., Cell Metabolism, 2022), and the full record is on the research summary.
Where can I buy Retatrutide for research?
Etched Research sells retatrutide on this page in 10mg and 30mg vials of lyophilized powder, for laboratory research use only, shipped to US addresses. The two sizes differ only in the amount of powder, and Janoshik Analytical results for both sizes are on the lab reference page.
Is retatrutide the same thing as LY3437943?
Yes. LY3437943 is the development code, and retatrutide is the generic name given to the same molecule. The early papers use the code, the later trials use the name.
Is there human data?
Yes. The trials above ran from a single-dose phase 1 study to a 537-person phase 3 trial, in adults with obesity or overweight, type 2 diabetes, or fatty liver disease. The longest published trial ran 48 weeks, so long-term data is not published yet.
Shipping, eligibility and what comes in the box: store FAQ →
For research use only. Not for human consumption.
