Retatrutide: What the Research Shows About the Triple-Receptor Agonist Peptide

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Retatrutide is one of the newest and most-discussed peptides in metabolic research. This guide summarizes what the published scientific literature has examined about retatrutide, its molecular profile, and how it is handled in a research setting. It is written for researchers and is not medical guidance.

What is retatrutide?

Retatrutide (developmental code LY3437943, CAS 2381089-83-2, molecular formula C₂₂₁H₃₄₂N₄₆O₆₈, molar mass ≈ 4731 g/mol) is a synthetic peptide engineered as a single molecule that activates three receptors at once: the GIP receptor, the GLP-1 receptor, and the glucagon receptor. Because of this “triple agonist” design, it is sometimes informally called “GLP-3” in the research-peptide community, a colloquial nickname rather than an official scientific classification. Retatrutide is an investigational drug candidate: it has been studied in clinical trials by its developer but is not approved for medical use.

Research-use note: Retatrutide is an investigational compound supplied strictly for laboratory research. It is not an approved drug, not a supplement, and not for human or animal consumption. Nothing below describes or endorses human use.

Evidence at a glance

Phase 2 human trials

Retatrutide produced the largest weight reductions yet reported for a drug in this class in published Phase 2 trials. It is still investigational and is not approved.

Why researchers are interested

It works on three receptors, GIP, GLP-1 and glucagon, where earlier drugs work on one or two. The glucagon arm is the addition that matters, because it raises energy expenditure on top of the appetite reduction the others provide. That is the accepted explanation for why its trial results beat them.

What the research found

Large weight reductionMean body weight loss of roughly 24 percent at the highest dose at 48 weeks (Jastreboff, NEJM 2023)
Better blood sugar controlReductions in HbA1c in adults with type 2 diabetes (Rosenstock, Lancet 2023)
Triple receptor activity confirmedReceptor pharmacology and pharmacokinetics characterised (Coskun, 2022)

Reported in the literature

Gastrointestinal effects were the most common in trials, including nausea, vomiting, diarrhoea and constipation, and they rose with dose.
Dose escalation was used specifically to limit those gastrointestinal effects.
Increases in heart rate were observed.
Long term safety is unknown. No Phase 3 outcome data has been published.

Findings are summarised from the sources listed under References on this page, and from approved product labelling where a compound has one. These are outcomes observed in published studies, not effects claimed for any person, and nothing here is a recommendation for human use.

How retatrutide works (the mechanism studied)

Most incretin-based peptides act on one or two receptors. Retatrutide is notable in the research literature for engaging three signaling pathways simultaneously: GIP, GLP-1, and glucagon. The preclinical molecular pharmacology of the compound was characterized by Coskun and colleagues (Cell Metabolism, 2022), which described how the single peptide activates all three receptors. This multi-receptor mechanism is the primary reason it became a subject of metabolic-research interest.

What researchers have studied

The published record on retatrutide consists largely of clinical-trial data generated by its developer. The most-cited studies include:

Obesity research: Jastreboff et al. (New England Journal of Medicine, 2023) reported a Phase 2 trial examining metabolic endpoints over 24–48 weeks.
Type 2 diabetes research: Rosenstock et al. (The Lancet, 2023) reported a Phase 2 trial examining glycemic markers.
Preclinical pharmacology: Coskun et al. (Cell Metabolism, 2022) characterized the compound’s triple-receptor activity.

These are investigations of an unapproved drug candidate, the findings belong to the published research record and do not represent approved or validated human uses.

Retatrutide compared with other incretin peptides

A useful way researchers categorize these compounds is by how many receptors they engage:

Single agonist (GLP-1 only), the earliest incretin class
Dual agonist (GIP + GLP-1), e.g. tirzepatide
Triple agonist (GIP + GLP-1 + glucagon), retatrutide

The addition of glucagon-receptor activity is the defining structural difference that distinguishes retatrutide in the literature.

Handling and reconstitution in the laboratory

Retatrutide is typically supplied as a lyophilized (freeze-dried) powder for research use. Standard laboratory practice is to reconstitute it with bacteriostatic water, swirl (not shake) until dissolved, and store the reconstituted solution refrigerated (2–8 °C). The lyophilized powder is generally stored frozen and protected from light. (General lab-handling notes, not usage instructions.)

For research use only

All products and information referenced here are intended strictly for laboratory and scientific research use only. They are not for human or animal consumption and are not drugs, foods, supplements, or medical devices. Retatrutide is an investigational compound that has not been approved by any regulatory authority for medical use. No statement here should be interpreted as medical advice.

Explore retatrutide and related research peptides

Retatrutide (GLP-3): verified CAS, formula, and specifications
Tirzepatide 20mg, GIP/GLP-1 dual agonist
Bacteriostatic Water 30ml, reconstitution diluent

References

Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity, A Phase 2 Trial. N Engl J Med. 2023. PubMed
Rosenstock J, et al. Retatrutide, a GIP/GLP-1/glucagon receptor agonist, for people with type 2 diabetes: a phase 2 trial. Lancet. 2023. PubMed
Coskun T, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist. Cell Metab. 2022. PubMed