Metabolic peptide research: GLP-1, GIP, glucagon and retatrutide
Research library
Peptides that act on the incretin and glucagon systems are among the most studied compounds in metabolic research today. This overview explains the three receptors involved and how single, dual and triple agonists differ, including retatrutide.
The three receptors
- GLP-1 receptor: glucagon-like peptide-1 is an incretin hormone released from the gut after eating. It is involved in insulin release, gastric emptying and appetite signalling in the brain.
- GIP receptor: glucose-dependent insulinotropic polypeptide is the second main incretin hormone, also involved in insulin release and fat tissue metabolism.
- Glucagon receptor: glucagon raises blood glucose by acting on the liver, and is also studied for its effects on energy expenditure and liver fat.
Single, dual and triple agonists
| Type | Receptors | Example compounds |
|---|---|---|
| Single agonist | GLP-1 | Semaglutide, liraglutide |
| Dual agonist | GLP-1 and GIP | Tirzepatide |
| Triple agonist | GLP-1, GIP and glucagon | Retatrutide (LY3437943) |
What is retatrutide?
Retatrutide (LY3437943) is a synthetic peptide developed by Eli Lilly that acts as an agonist at all three receptors. Adding glucagon receptor activity to the incretin pair is the reason it attracts so much research interest: it lets researchers study the combined effect of the three pathways on glucose control, energy expenditure and liver fat.
Retatrutide has been studied in phase 2 clinical trials, with results published in the New England Journal of Medicine in 2023, and is in a phase 3 programme. It is not an approved medicine in South Africa or elsewhere. Eli Lilly has said it plans to apply for US approval in early 2027; a planned application is not an approval.
Where MOTS-c fits
MOTS-c is studied in metabolic research by a different route: it is a mitochondrial-derived peptide acting through cellular energy sensing (AMPK), not through the incretin or glucagon receptors.
Metabolic research peptides at Meytrix
- Retatrutide research pens, 30mg, 40mg and 60mg, with published batch COAs
- MOTS-c 40mg research pen
- Reta Glow Stack
References
- Coskun T, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist. Cell Metab. 2022;34(9):1234-1247.
- Jastreboff AM, et al. Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial. N Engl J Med. 2023;389(6):514-526.
Frequently asked questions
What is retatrutide?
Retatrutide (LY3437943) is an investigational synthetic peptide that acts on three receptors: GLP-1, GIP and glucagon. It is known as a triple agonist.
How is retatrutide different from tirzepatide and semaglutide?
Semaglutide acts on the GLP-1 receptor only, tirzepatide acts on GLP-1 and GIP receptors, and retatrutide acts on GLP-1, GIP and glucagon receptors.
Is retatrutide approved?
No. Retatrutide is an investigational compound in clinical trials and is not an approved medicine in South Africa or elsewhere. Meytrix supplies it for laboratory research use only.
Where can I buy retatrutide in South Africa?
Meytrix supplies retatrutide research pens (30mg, 40mg and 60mg) from Cape Town, with published batch Certificates of Analysis, for laboratory research use only.
All Meytrix products are supplied for laboratory research use only and are not for human consumption.