UBT251 vs Retatrutide: Understanding the Scientific Differences Between Two Triple Receptor Agonists

• Same targets, different molecules. Both activate GLP-1R, GIPR and GCGR, but their sequences, modifications and receptor balance are not the same.
• Different developers. UBT251: The United Laboratories (through The United Bio-Technology (Hengqin) Co., Ltd.), licensed to Novo Nordisk outside Greater China in 2025. Retatrutide (LY3437943): Eli Lilly and Company.
• Different stages. Retatrutide has a published Phase 2 trial and a Phase 3 program (TRIUMPH). UBT251 has Phase 1 and Phase 2 studies reported by its developers, with a global Phase 1b/2a study under way.
• Reported results: UBT251’s 24-week Phase 2 study reported a mean body-weight change of up to −19.7% (placebo −2.0%). Retatrutide’s 80-week Phase 3 TRIUMPH-1 reported up to about −28% (placebo about −2%).
• No head-to-head study. Those studies differ in population, length and design, so their results can’t rank one compound above the other.
• Identity must be tested, not assumed. A certificate of analysis should confirm each compound by mass spectrometry; a class label or a purity figure alone does not.

UBT251 is an investigational, long-acting synthetic peptide designed to activate three class B1 G protein-coupled receptors:

• the glucagon-like peptide-1 receptor (GLP-1R)
• the glucose-dependent insulinotropic polypeptide receptor (GIPR)
• the glucagon receptor (GCGR)

It was discovered by The United Laboratories International Holdings. In March 2025 its subsidiary, The United Bio-Technology (Hengqin) Co., Ltd., licensed rights outside mainland China, Hong Kong, Macau and Taiwan to Novo Nordisk. The developer has reported Phase 1 and Phase 2 studies in China, and Novo Nordisk has started a global Phase 1b/2a study. Research suppliers sometimes list UBT251 as “Vistrutide”, a name that does not come from the developer. See our UBT251 research overview for more.

Retatrutide (development code LY3437943) is an investigational triple receptor agonist developed by Eli Lilly and Company. Like UBT251, it targets GLP-1R, GIPR and GCGR.

Its program includes a Phase 2 trial published in the New England Journal of Medicine in 2023 (338 adults, 48 weeks) and a Phase 3 program called TRIUMPH. TRIUMPH-1 (ClinicalTrials.gov NCT05929066) is an 80-week, randomized, double-blind, placebo-controlled study in 2,339 adults; Lilly announced its topline results in May 2026. As of October 2026, retatrutide has the larger body of late-stage clinical evidence of the two.

Reference identifiers: CAS 2381089-83-2; molecular formula C₂₂₁H₃₄₂N₄₆O₆₈; molecular weight about 4731.3 g/mol. See our retatrutide research overview and retatrutide pharmacokinetics pages.

Key distinction: sharing the same receptor targets does not mean two compounds have the same sequence, receptor activation profile, pharmacokinetics or biological effects.

A triple agonist is one peptide engineered to activate three related receptors. All three belong to the class B1 (secretin-family) GPCRs, which bind their peptide ligands in two steps: the receptor’s extracellular domain captures the peptide’s C-terminal region, and the N-terminal region then activates the transmembrane core.

GLP-1 receptor signaling

GLP-1 receptors are studied in pancreatic beta-cell, gut and central nervous system models. In the laboratory, activation is usually measured as intracellular cAMP accumulation, along with β-arrestin recruitment and receptor internalization.

GIP receptor signaling

GIP receptors are studied in pancreatic islet and adipose tissue models. A central research question is how GIP receptor activity combines with GLP-1 receptor activity when one molecule engages both.

Glucagon receptor signaling

Glucagon receptors are expressed mainly in the liver and studied in models of hepatic glucose output and lipid metabolism. Adding glucagon receptor activity makes the overall profile more complex, which is why triple agonists are compared receptor by receptor.

All three receptors couple mainly to G_s and raise cAMP. What sets one triple agonist apart from another is its balance: its relative potency and efficacy at each receptor. For background on the class, see what a triple agonist research peptide is.

No. They are separately discovered, separately developed compounds. A shared “GLP-1/GIP/glucagon triple agonist” label describes their targets, not their chemistry. Peptides in the same class can differ in:

• amino acid sequence and non-natural residues
• lipidation and other modifications that set half-life
• relative potency at each of the three receptors
• receptor binding kinetics and signaling bias
• chemical and metabolic stability
• pharmacokinetic behavior
• analytical properties, such as molecular mass and HPLC retention

Each of these has to be measured for each compound, not inferred from the class.

The figures below are as reported by the developers or published papers. They come from separate studies and are summarized here for research context only.

UBT251

• Phase 2 (China), overweight and obesity: a randomized, double-blind, placebo-controlled study in 205 adults over 24 weeks. The developers reported a mean body-weight change of up to −19.7% (−17.5 kg) in the highest group, versus −2.0% with placebo, and described the safety profile as consistent with other incretin-class compounds. Detailed data were to be presented at a scientific congress; we have not found a peer-reviewed paper yet.
• Phase 2 (China), type 2 diabetes: the developers reported an HbA1c change of up to −2.16% after 24 weeks, versus −1.77% with a semaglutide comparator and −0.66% with placebo.
• Phase 1: a single-ascending study reported linear pharmacokinetics and a mean half-life of roughly 137 to 170 hours.
• Next: Novo Nordisk’s global Phase 1b/2a study (around 330 participants, up to 28 weeks) has topline data expected in 2027.

Retatrutide

• Phase 2 (NEJM, 2023): 338 adults with obesity over 48 weeks. The highest group showed a mean body-weight change of −24.2% at 48 weeks, versus −2.1% with placebo. Gastrointestinal events were the most commonly reported adverse events.
• Phase 3 TRIUMPH-1 (NCT05929066): 2,339 adults with obesity or overweight over 80 weeks. Lilly’s May 2026 topline reported mean body-weight changes of up to about −28% in the highest group, versus about −2% with placebo. Reports using a different statistical analysis give about −25% versus about −4%; check the primary publication for the definitive figures.

Why these results can’t be compared directly: the studies enrolled different populations (Chinese adults versus global populations), ran for different lengths (24 versus 48 and 80 weeks), and used different designs and endpoints. A 24-week result and an 80-week result are not like for like. Only a properly designed head-to-head study could say whether one compound performs differently from the other, and none has been reported.

All of these are clinical trial findings for investigational compounds. Neither compound is an authorized product for any use, and these findings say nothing about research-grade material sold for laboratory use.

For analytical work, two compounds that share a pharmacological class are still separate chemical entities. The checks that matter:

• Identity: confirm the sample is the claimed compound, usually by mass spectrometry (ESI-MS or MALDI-TOF) against the expected molecular weight.
• Purity: the share of the target compound relative to detectable impurities, typically by reversed-phase HPLC.
• Peptide content: the measured amount of target peptide in the material, which matters for preparing accurate stock concentrations.
• Stability: how storage, temperature, light and time affect chemical integrity.

High purity alone does not prove correct identity, receptor activity or equivalence to another compound. This is especially important for UBT251, whose structure is not widely published. Learn how to read a certificate of analysis, see HPLC testing for peptides, and find batch certificates in NuRev’s COA library.

Engaging three metabolic receptors with one molecule may produce signaling that differs from single- or dual-receptor activation. Active research areas include receptor pharmacology and selectivity, intracellular signaling and bias, structure–activity relationships, peptide stability, and how the three pathways interact. UBT251 and retatrutide are two distinct examples of this class. For more on related receptor targets, see the metabolic peptide receptor overview.

UBT251 and retatrutide show why the triple agonist class draws so much research attention. Both target the GLP-1, GIP and glucagon receptors, but they differ in molecular identity, developer, and the extent of published evidence. For researchers, the lesson is a basic one: compounds with the same receptor targets are not automatically chemically or biologically equivalent, and each must be characterized on its own.

1. Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine, 2023. PubMed 37366315 · doi:10.1056/NEJMoa2301972
2. TRIUMPH-1 (retatrutide Phase 3). ClinicalTrials.gov NCT05929066
3. Novo Nordisk. Triple agonist UBT251 Phase 2 topline results (company announcement), February 24, 2026. novonordisk.com
4. The United Laboratories and Novo Nordisk. Exclusive license agreement for UBT251 (company announcement), March 24, 2025.
5. Ongoing studies: ClinicalTrials.gov search for UBT251 and PubMed search for UBT251.

This article is for scientific and educational purposes. It summarizes published research on investigational compounds and is not guidance for human or veterinary use. NuRev research materials are for laboratory research use only and are not the investigational products used in clinical studies.