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Retatrutide vs Amycretin: A Triple Agonist Against a Single-Molecule Amylin + GLP-1 Agonist

Retatrutide activates three receptors (GIP, GLP-1, glucagon); amycretin is a Novo Nordisk single molecule that activates the amylin and GLP-1 receptors and is being developed as both a weekly injection and a daily oral tablet. Retatrutide reported 24.2% mean weight reduction at 48 weeks in Phase 2; subcutaneous amycretin reported up to 24.3% at 36 weeks in a small early-phase study and up to 14.5% in a type 2 diabetes Phase 2. Neither is approved, they have never been compared head-to-head , and New-U does not sell amycretin.

No head-to-head results exist, and the amycretin data are earlier-stage. The amycretin figures come from a small Phase 1b/2a study and a diabetes-population Phase 2; retatrutide has a larger obesity Phase 2 and reported Phase 3 toplines. Cross-trial percentages are indicative only. Research context; nothing here is medical or dosing guidance. Regulatory and trial status is as of September 2026.

At a glance

Retatrutide Amycretin Receptor targets GIP + GLP-1 + glucagon Amylin + GLP-1 (one molecule) Developer Eli Lilly (LY3437943) Novo Nordisk Format Once-weekly injection (trials) Once-weekly injection and once-daily oral tablet Obesity data 24.2% at 48 wk (Phase 2, 12 mg arm) Up to 24.3% at 36 wk (Phase 1b/2a, subcutaneous) Type 2 diabetes data 20.8% at 80 wk (TRIUMPH-2, 12 mg, sponsor-reported) Up to 14.5% subcutaneous, 10.1% oral (Phase 2) Stage Phase 3 (TRIUMPH); no approval Clinical development; no approval Research access GLP1-RC-RT (retatrutide reference) Not sold: proprietary

Three receptors or two

Retatrutide combines two incretin signals with a glucagon signal. Amycretin pairs GLP-1 with amylin, a separate satiety hormone (preclinical work suggests it may also improve leptin sensitivity), and does so inside one molecule rather than in a two-drug combination like CagriSema. That single-molecule design is what makes an oral formulation realistic, and it means one pharmacokinetic profile and one manufacturing stream instead of two.

The two molecules answer different questions. Retatrutide asks how much a third receptor (glucagon) adds to the two incretins. Amycretin asks how much an amylin signal adds to GLP-1, and whether it can be delivered by mouth.

The oral question

Peptides are normally digested, so an oral peptide that reaches meaningful exposure is an engineering result in its own right. In the type 2 diabetes Phase 2, oral amycretin produced up to 10.1% weight reduction against 14.5% for the subcutaneous form, so the format trade-off is measurable. In the trials summarised here retatrutide was given by injection. For the wider question across the class, see oral vs injectable GLP-1 research.

What the trials showed

Retatrutide (Phase 2, NEJM 2023, n=338): 24.2% mean weight reduction at 48 weeks on the 12 mg arm (22.8% at 8 mg, 17.1% at 4 mg) against 2.1% on placebo. In TRIUMPH-2, in people with type 2 diabetes, Lilly reported 20.8% at 80 weeks on 12 mg.

Amycretin, subcutaneous (Phase 1b/2a, The Lancet 2025, n=125 adults with overweight or obesity): mean weight reductions of 24.3% (60 mg arm) and 22.0% (20 mg arm) at 36 weeks, in a small early-phase study.

Amycretin, Phase 2 in type 2 diabetes (n=448): up to 14.5% (subcutaneous) and 10.1% (oral) against about 2.5–2.6% on placebo, in people inadequately controlled on metformin with or without an SGLT2 inhibitor.

Two points keep the numbers honest. People with type 2 diabetes typically lose less weight on incretin-class drugs than people without it, so the 14.5% and 20.8% figures should be read against each other, not against the obesity figures. And the amycretin obesity figures come from a much smaller and shorter study than retatrutide’s Phase 2, so they carry wider uncertainty.

Research access

Amycretin is a proprietary Novo Nordisk molecule and New-U does not sell it. The amycretin research guide sets out the pipeline in more detail.

Research takeaway

Retatrutide is a three-receptor weekly injection; amycretin is a two-receptor (amylin + GLP-1) molecule in injectable and oral formats.

Amycretin’s obesity figure comes from a small early study; retatrutide’s comes from a larger Phase 2 and Phase 3 toplines.

Diabetes-population results (14.5% and 20.8%) belong in a column of their own.

Neither is approved, no head-to-head results exist, and the other compound is proprietary and not sold by New-U.

Primary sources

New England Journal of Medicine — Triple–Hormone-Receptor Agonist Retatrutide for Obesity (Jastreboff et al., 2023)

Eli Lilly — TRIUMPH-2 and TRIUMPH-3 topline results

The Lancet — Amycretin, a unimolecular GLP-1 and amylin receptor agonist, administered subcutaneously: Phase 1b/2a (2025)

Retatrutide as a research reference (GLP1-RC-RT)

New-U catalogues laboratory research material under GLP1-RC-RT (retatrutide reference). Amycretin is a proprietary Novo Nordisk molecule and is not sold. The trial results above describe the sponsors’ investigational products, not this material. Published Certificates of Analysis are available for the batches listed in the COA library. Research use only – all claims made on this site are for testing and research use only.

Frequently asked questions

Is amycretin better than retatrutide?

No trial has compared them, and the amycretin data are earlier-stage. Separate studies reported up to 24.3% at 36 weeks for subcutaneous amycretin (small Phase 1b/2a) and 24.2% at 48 weeks for retatrutide (Phase 2). Research context only.

How does amycretin differ from retatrutide?

Amycretin is a single molecule agonising the amylin and GLP-1 receptors, in development as a weekly injection and a daily tablet. Retatrutide agonises GIP, GLP-1 and glucagon receptors and has been studied as a weekly injection.

Is amycretin approved?

As of September 2026, no. The sources reviewed report no marketing authorisation, and amycretin remains in clinical development.

Why is an oral form notable?

Peptides are normally digested in the gut, so an oral peptide that reaches meaningful exposure is an engineering result. In the type 2 diabetes Phase 2, oral amycretin produced up to 10.1% weight reduction against 14.5% for the injectable form.

Can amycretin be bought as a research compound?

No. It is proprietary and New-U does not sell it.

External links are provided for research reference only; New-U is not affiliated with the cited organisations. All figures are published trial results shown for research context, not dosing guidance. New-U Research Compounds supplies research compounds strictly for laboratory research use only — not for human consumption .

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