Mazdutide is the first dual GLP-1/glucagon receptor agonist to complete a dedicated Phase 3 obesity programme and to reach a national medicines regulator. The GLORY-1 trial, published in the New England Journal of Medicine, tested a once-weekly oxyntomodulin analogue developed by Innovent Biologics under licence from Eli Lilly in Chinese adults with overweight or obesity. Both active doses beat placebo on the primary weight-change endpoint. China's National Medical Products Administration has since authorised a pharmaceutical presentation.
That sequence is easy to over-read from a United Kingdom desk. A completed Phase 3 trial and a Chinese product licence do not create an MHRA marketing authorisation, a NICE appraisal, or a lawful consumer medicine. They also do not authenticate research-chemical vials sold under the same international non-proprietary name. This article reports the published trial, places it against the other dual agonists already profiled on this site, and restates the UK legal position. It is not a protocol. It does not describe how to obtain, prepare or administer mazdutide. No consumption or self-administration advice.
1. What was published
Ji and colleagues reported GLORY-1 (NCT05607680) in the New England Journal of Medicine in May 2025. The trial randomised 610 Chinese adults with overweight or obesity to once-weekly subcutaneous mazdutide 4 mg, mazdutide 6 mg, or matched placebo for 48 weeks, with the primary analysis of percentage change in body weight at week 32. Participants had a body-mass index of at least 28 kg/m², or at least 24 kg/m² with at least one weight-related comorbidity — thresholds that follow Chinese rather than NICE obesity criteria and should not be mapped onto a UK clinic population without that caveat.
The study was sponsored in China. It is a single-country Phase 3 programme, not a multi-region filing package of the kind that typically underpins an MHRA or EMA obesity licence. That does not diminish the internal validity of the randomised comparison. It does limit how far the point estimates can be generalised to European adults, to different background diets, or to people already treated with a licensed incretin.
2. What mazdutide is — and is not
Mazdutide (IBI362; formerly LY3305677) is a synthetic analogue of oxyntomodulin. Endogenous oxyntomodulin is a 37-residue proglucagon peptide that activates both the GLP-1 receptor and the glucagon receptor. The pharmaceutical analogue is fatty-acylated to extend plasma half-life so that once-weekly administration is pharmacologically plausible. Receptor co-agonism is the mechanistic claim: GLP-1-receptor activity is expected to reduce energy intake; glucagon-receptor activity is hypothesised to increase energy expenditure and to shift hepatic lipid handling. Those are experimental rationales, not proven human energy-balance mechanisms at the doses used in GLORY-1.
Mazdutide is not semaglutide, not tirzepatide, and not a glucagon-only agonist. It sits in the same mechanistic class as survodutide (Boehringer Ingelheim / Zealand) and pemvidutide (Altimmune), both of which have later-stage metabolic and MASH programmes and neither of which is MHRA-licensed. It is also distinct from CagriSema, which pairs a GLP-1 agonist with an amylin analogue rather than a glucagon-receptor agonist. Class language that collapses these programmes into a single "next incretin" is not supported by the primary literature.
3. Efficacy, as reported
At the week-32 primary analysis both active arms produced statistically significant reductions in body weight versus placebo. By week 48, published and sponsor summaries place the mean reduction in the 4 mg arm at around 11–12% and in the 6 mg arm at around 14%, against essentially no change on placebo. A substantially higher proportion of participants on mazdutide than on placebo reached the conventional 5%, 10% and 15% weight-loss thresholds. Exact least-squares means depend on the estimand — treatment-policy versus hypothetical on-treatment — and on whether the week-32 or week-48 time point is cited. Readers should use the NEJM tables, not secondary recaps, when a percentage is going to be reused.
Two limits belong next to those figures. First, GLORY-1 used a Chinese BMI schedule and a Chinese trial population; the same milligram doses have not been shown, in a published Phase 3 trial, to reproduce those percentages in a UK or European cohort. Second, a 48-week weight-change endpoint is not a cardiovascular-outcome trial, not a MASH histology trial, and not a head-to-head against semaglutide 2.4 mg or tirzepatide. SURMOUNT-5 answered the last of those questions for tirzepatide versus semaglutide. GLORY-1 does not.
Glycaemic and cardiometabolic secondaries moved in the direction expected of a GLP-1-containing agonist — improvements in glycaemia among participants with prediabetes or type 2 diabetes, and favourable shifts in waist circumference and selected lipids. Those are supportive findings inside an obesity trial. They are not a substitute for the dedicated DREAMS type 2 diabetes programme, and they are not a UK licensed indication.
4. Safety, as reported
The adverse-event profile was dominated by gastrointestinal events typical of GLP-1-receptor agonism: nausea, diarrhoea, vomiting and decreased appetite, mostly mild to moderate and concentrated during dose escalation. Discontinuation for adverse events was higher on active drug than on placebo, as it has been in every large incretin obesity programme. Heart rate rose modestly, again consistent with the class. The published report did not identify a new, unexpected safety signal that would distinguish mazdutide from other late-stage dual GLP-1/glucagon agonists.
What the paper does not settle is equally important. GLORY-1 is not powered for rare events. It does not resolve class questions that UK regulators have already flagged for licensed GLP-1 and dual GIP/GLP-1 agonists — acute pancreatitis, biliary disease, pulmonary aspiration under anaesthesia, and the very rare NAION signal attached specifically to semaglutide. Those MHRA communications apply to authorised UK products with an SmPC. They are not a safety file for unlicensed mazdutide, and the absence of a matching MHRA warning is not evidence of absence of risk.
Glucagon-receptor agonism adds a theoretical hepatic and heart-rate burden that selective GLP-1 agonists do not carry. Survodutide and pemvidutide programmes have watched liver enzymes and pulse for the same reason. GLORY-1's liver-enzyme and pulse data are part of that class file; they are not a completed hepatic-safety argument.
5. The rest of the dual-agonist class
Three dual GLP-1/glucagon agonists now have mature enough public data to be discussed as a class rather than as isolated press releases.
- Mazdutide — Phase 3 obesity (GLORY-1) published; a higher-dose obesity programme (GLORY-2) and a type 2 diabetes programme (DREAMS-1, DREAMS-2) have reported at congress or in sponsor releases; a Chinese product licence exists.
- Survodutide — Phase 2 obesity and Phase 3 visceral- and liver-fat data are already on this site. No UK licence.
- Pemvidutide — Phase 2b MASH histology in The Lancet, already covered here. No UK licence.
The class is therefore no longer preclinical. It is also not interchangeable. Dose, glucagon-receptor bias, trial population and regulatory status differ. Citing mazdutide's Chinese licence as if it upgraded survodutide or pemvidutide is a category error. Citing any of the three as a research-chemical equivalent of Wegovy or Mounjaro is another.
6. China has a licence. The United Kingdom does not.
In June 2025 the National Medical Products Administration authorised mazdutide injection (marketed in China as Xinermei) for long-term weight management in adults with obesity, or overweight plus at least one weight-related comorbidity. A type 2 diabetes indication has been pursued from the DREAMS programme. That is a national marketing authorisation in one jurisdiction.
It is not an MHRA marketing authorisation. Mazdutide does not appear on the UK register of licensed medicines for obesity or diabetes. It has no UK SmPC, no NICE technology appraisal, and no place in NICE NG246 or TA1026, which address semaglutide and tirzepatide respectively. The licensed UK peptide and incretin options for chronic weight management remain, at the time of writing, liraglutide (Saxenda), semaglutide (Wegovy) and tirzepatide (Mounjaro) — each a prescription-only medicine, each with defined eligibility and safety information.
Under the Human Medicines Regulations 2012 and the Medicines Act 1968, a substance presented as a medicine for the treatment of obesity, or supplied with medicinal claims, is a medicinal product. An NMPA licence does not authorise UK supply. Importation, sale or advertisement of unlicensed mazdutide as a slimming or diabetes medicine engages that framework. Mazdutide is not, on current public lists, a Misuse of Drugs Act 1971 controlled drug; absence of MDA scheduling is not a permission to supply it as a medicine. The MHRA's 2026 research-peptide labelling guidance continues to apply to grey-market peptide presentations.
7. Research-chemical listings are a different object
Pharmaceutical mazdutide is a defined, fatty-acylated peptide in a licensed Chinese presentation, manufactured to a filed specification. Research-chemical listings that reuse the name "mazdutide" or the code IBI362 are not that product. Sequence identity, fatty-acid side chain, counter-ion, sterility and endotoxin are not established by a vendor catalogue line. A usable certificate of analysis for any such listing would need intact-mass confirmation of the acylated sequence, a chromatogram with method, and independent ISO-laboratory testing. A generic "purity >98%" claim without method is not that certificate.
Peptide Data does not treat research-chemical mazdutide as an evidence-graded intervention. The GLORY-1 evidence grade attaches to the pharmaceutical molecule in the trial. It does not transfer to an uncharacterised vial. Affiliate relationships, where present elsewhere on this site, are disclosed on the pages that carry them and do not change that distinction.
8. What researchers can and cannot say
Permissible, on the published record: mazdutide is a once-weekly dual GLP-1/glucagon agonist; GLORY-1 met its primary weight-change endpoint at both tested doses in Chinese adults; mean reductions at week 48 sit in the low-to-mid teens of percent body weight on the 6 mg arm, estimand-dependent; gastrointestinal adverse events dominated, in line with the incretin class; China has authorised a pharmaceutical product; the United Kingdom has not.
Not permissible: that mazdutide treats, cures or prevents obesity, diabetes or liver disease as a statement of fact outside the licensed Chinese indication; that GLORY-1 is a UK or European evidence base; that research-chemical mazdutide is the Innovent/Lilly product; that dual-agonist research peptides are a legal or pharmacological substitute for Wegovy or Mounjaro; any reconstitution volume, milligram schedule, titration ladder or injection-site instruction for human use.
9. What happens next
Three watch-items matter more than a second recap of the week-48 means. First, whether Innovent and Lilly file in Europe or run a Western Phase 3 obesity trial — without that, MHRA assessment does not start. Second, GLORY-2 and any cardiovascular or MASH programme, which would change the evidence grade for specific questions and still would not, on their own, create a UK licence. Third, any MHRA or Yellow Card communication that names dual GLP-1/glucagon agonists as a class. Until one of those three moves, mazdutide remains a well-documented foreign Phase 3 molecule and an unlicensed substance in the United Kingdom.
Peptide Data will update the mazdutide compound profile if a UK regulatory decision or a peer-reviewed human dataset changes the evidence grade or the legal status. Grades do not move on a press release alone.
This article is AI-researched and editorially reviewed. It is provided for research and educational purposes only and is not medical advice. Research peptides are not licensed for human consumption in the UK.