UBT251 and retatrutide are both GLP-1/GIP/glucagon triple receptor agonists, the so-called "triple G" class designed to beat dual agonists like tirzepatide on weight loss. The key difference is maturity. Retatrutide (Eli Lilly) has completed pivotal phase 3 trials showing up to 28.3% average weight loss at 80 weeks. UBT251 (originally The United Laboratories, now licensed to Novo Nordisk) is years behind, with a 36-patient phase 1b and Chinese phase 2 data showing up to 19.7% weight loss at 24 weeks. Neither drug is FDA approved as of mid-2026.
This comparison breaks down what is actually known about each molecule, what is still unproven, and why the two cannot be judged on weight-loss percentages alone given how differently the trials were run.
Quick comparison table
| Feature | UBT251 | Retatrutide |
|---|---|---|
| Drug class | GLP-1 / GIP / glucagon triple agonist | GLP-1 / GIP / glucagon triple agonist |
| Originator | United Bio-Technology (Hengqin), a subsidiary of The United Laboratories (TUL) | Eli Lilly |
| Current owner ex-China | Novo Nordisk (licensed March 2025) | Eli Lilly |
| Dosing | Once weekly subcutaneous | Once weekly subcutaneous |
| Development stage | Early phase 2 (China); global trials starting | Phase 3 complete (TRIUMPH program) |
| Best weight loss reported | 19.7% at 24 weeks (phase 2, China) | 28.3% at 80 weeks (phase 3 TRIUMPH-1) |
| Phase 1 weight loss | 15.1% at 12 weeks (highest dose) | Not the headline data point; phase 2/3 lead |
| FDA approval | No | No (investigational) |
| Likely earliest US availability | Late this decade | Projected 2027 to 2028 |
What UBT251 is and who owns it
UBT251 is a long-acting synthetic peptide that activates three gut and pancreatic hormone receptors at once: GLP-1, GIP, and glucagon. That is the same triple-receptor target set used by retatrutide, which is why the two are direct conceptual rivals.
The molecule was developed by United Bio-Technology (Hengqin) Co., Ltd., a wholly owned subsidiary of The United Laboratories International Holdings Limited (TUL), a Hong Kong-listed pharmaceutical company. In March 2025, Novo Nordisk signed an exclusive license agreement giving it worldwide rights to UBT251 outside the Greater China region (mainland China, Hong Kong, Macau, and Taiwan, where United Biotechnology kept the rights).
The deal terms tell you how much Novo valued the asset:
- 200 million US dollars upfront
- Up to 1.8 billion US dollars in potential milestone payments
- Tiered royalties on net sales
For Novo Nordisk, UBT251 is a way to re-enter the triple-agonist race after the lower-than-expected CagriSema readouts. The drug is being developed primarily for obesity and type 2 diabetes.
What retatrutide is and who owns it
Retatrutide (development code LY3437943) is Eli Lilly's investigational triple agonist. It is a 39-amino-acid single peptide engineered from a GIP peptide backbone, with a fatty-acid chain that extends its half-life to allow once-weekly dosing. It is a full agonist at all three receptors, but its activity is deliberately imbalanced, with markedly higher potency at the GIP receptor than at the GLP-1 and glucagon receptors.
That glucagon component is the part that separates triple agonists from tirzepatide. Glucagon receptor activation raises energy expenditure and supports liver fat reduction, which is thought to drive the larger weight loss seen in this class. For a deeper breakdown, see our guide to the retatrutide mechanism of action.
Trial data side by side
This is where the comparison gets nuanced. The two drugs have not been studied head to head, and the trials differ in length, population, and dose, so the raw percentages are not directly comparable.
UBT251 phase 1b
The first human efficacy signal for UBT251 came from a randomized, double-blind, placebo-controlled phase 1b study run in China:
- 36 patients enrolled across three dose groups
- Weekly subcutaneous injections for 12 weeks
- Escalating regimens: 1 mg; 1 mg/3 mg; 1 mg/3 mg/6 mg
- Highest-dose group (6 mg): average 15.1% weight reduction at 12 weeks
- Placebo group: essentially no weight loss
A 15.1% drop in 12 weeks is a strong early signal, but 36 patients is a tiny sample and 12 weeks is a short window. Early-phase numbers like this should be read as proof of concept, not as a number you can stack against a long phase 3 result.
UBT251 phase 2 (China)
In 2026, Novo Nordisk and TUL reported phase 2 results from China:
- Obesity trial: 2 mg, 4 mg, and 6 mg doses versus placebo, baseline mean body weight 92.2 kg
- Up to 19.7% mean weight loss (about 17.5 kg) at 24 weeks versus 2% for placebo
- Type 2 diabetes trial: HbA1c reduction up to 2.16% and weight loss up to 9.8% at 24 weeks, with improvements relative to both placebo and semaglutide 1 mg
- Tolerability described as consistent with other incretin-based therapies
Novo has said it plans to start a global phase 2 type 2 diabetes trial in the second half of 2026 and expects topline weight-management phase 1b/2a data around 2027.
Retatrutide phase 2
Retatrutide's phase 2 obesity data were published in the New England Journal of Medicine in 2023:
- Obesity (48 weeks): up to 24.2% mean weight loss at the 12 mg dose versus 2.1% with placebo
- Type 2 diabetes (36 weeks): up to 16.9% mean weight loss at the 12 mg dose
Retatrutide phase 3 (TRIUMPH program)
Retatrutide's pivotal evidence comes from the large TRIUMPH program. TRIUMPH-1 enrolled 2,339 participants and ran for 80 weeks. Results are reported under two statistical measures: the efficacy estimand (the effect while patients actually stay on treatment) and the more conservative treatment-regimen estimand (which counts people who stop early). At 80 weeks under the efficacy estimand:
- 4 mg dose: 19.0% average weight loss
- 9 mg dose: 25.9% average weight loss
- 12 mg dose: 28.3% average weight loss, versus 2.2% with placebo
Under the treatment-regimen estimand, the 12 mg figure was 25.0%. In a 104-week extension, participants originally assigned to 12 mg reached up to 30.3% average weight loss under the efficacy estimand.
A separate phase 3 trial, TRIUMPH-4 (in adults with obesity and knee osteoarthritis), reported 28.7% average weight loss at the 12 mg dose over 68 weeks. You can read more in our summary of the retatrutide clinical trial results.
| Trial milestone | UBT251 | Retatrutide |
|---|---|---|
| Phase 1 readout | 15.1% at 12 weeks (n=36) | Dose-finding only |
| Phase 2 obesity | 19.7% at 24 weeks (China) | 24.2% at 48 weeks (NEJM) |
| Phase 2 T2D | 9.8% weight loss, 2.16% HbA1c at 24 weeks | 16.9% at 36 weeks |
| Phase 3 obesity | None yet | 28.3% at 80 weeks (TRIUMPH-1) |
| Sample size to date | Tens to low hundreds | Thousands |
Why you cannot just compare the percentages
It is tempting to line up "19.7%" against "28.3%" and call retatrutide the winner, but that comparison is unfair to both molecules:
- Time on drug differs. UBT251's headline number is at 24 weeks. Retatrutide's headline is at 80 weeks. Incretin weight loss keeps climbing for a year or more, so a shorter trial almost always shows a smaller number.
- Populations differ. UBT251's data so far are from Chinese patients with a mean baseline weight of 92.2 kg, while retatrutide's phase 3 enrolled a larger, more diverse population at higher baseline weights. Body composition and starting weight affect percentage loss.
- Doses are not matched. The two drugs use different milligram scales and titration schedules, so a 6 mg UBT251 dose is not equivalent to a 6 mg retatrutide dose.
- Statistical maturity differs. Retatrutide's numbers come from thousands of patients in pivotal trials; UBT251's come from far smaller early studies that can move once larger trials run.
The honest read is that UBT251 has shown a promising early efficacy signal in the same ballpark as the rest of the triple-agonist class, but it has not yet proven anything at phase 3 scale or duration.
Development stage and timeline
This is the most decisive difference between the two.
Retatrutide has finished its pivotal obesity trials and is heading toward regulatory submission. Industry timelines point to an NDA filing around late 2026, with potential FDA approval in 2027 or 2028 depending on review type. For the current outlook, see when retatrutide will be available.
UBT251 is years behind. The Chinese phase 2 data are encouraging, but Novo Nordisk is only now moving it into global trials, with key weight-management data not expected until around 2027. Realistically, UBT251 is a late-decade prospect at the earliest in Western markets.
Important for both: neither UBT251 nor retatrutide is FDA approved or available by prescription as of mid-2026. Retatrutide remains investigational, and any product sold online claiming to be retatrutide is unregulated. See our notes on compounded retatrutide before considering any non-clinical source.
How they fit into the wider class
If you are mapping the triple-agonist landscape, it helps to see where each drug sits against neighbors:
- Retatrutide vs tirzepatide: the most relevant near-term comparison, since tirzepatide is an approved dual agonist. See retatrutide vs tirzepatide.
- Survodutide vs retatrutide: survodutide is a Boehringer Ingelheim GLP-1/glucagon dual agonist, another rival in development. See survodutide vs retatrutide.
- UBT251 is Novo Nordisk's entry into the triple-G space, positioning it to compete directly with Lilly's retatrutide once both reach the market.
Bottom line
Retatrutide is the more proven molecule by a wide margin, with phase 3 evidence in thousands of patients and a clear path toward regulatory filing. UBT251 is an earlier-stage but credible challenger, backed by Novo Nordisk's resources and a phase 1b/phase 2 signal that lands within the triple-agonist range. Watch UBT251's first global trial readouts (expected around 2027) before drawing firm conclusions; until then, retatrutide is the benchmark this class is measured against.
Frequently asked questions
Is UBT251 the same as retatrutide?
No. They are different molecules made by different companies, though both target the same three receptors (GLP-1, GIP, and glucagon). Retatrutide is Eli Lilly's; UBT251 originated at The United Laboratories and is now licensed to Novo Nordisk outside Greater China.
Which one causes more weight loss?
On the data available, retatrutide has shown larger numbers (up to 28.3% at 80 weeks in phase 3) than UBT251 (up to 19.7% at 24 weeks in phase 2). The trials differ in length and population, so the gap partly reflects how the studies were run rather than a proven head-to-head difference.
Is UBT251 available to buy?
No. UBT251 is in early clinical development and is not approved or sold anywhere as a finished medicine. Any product marketed under that name is unregulated and unverified.
When could UBT251 be approved?
There is no set date. With global trials only starting and key data expected around 2027, a Western approval would likely be late this decade at the earliest, well behind retatrutide.
Does UBT251 use the glucagon receptor like retatrutide?
Yes. Both drugs activate the glucagon receptor in addition to GLP-1 and GIP. The glucagon component is what defines the triple-agonist class and is thought to boost energy expenditure and liver fat reduction beyond what dual agonists achieve.
This article is for informational purposes only and is not medical advice; consult a qualified clinician before making any treatment decisions.
