Mazdutide: what it is, GLORY and DREAMS trial results, side effects and approval status

Mazdutide is a single synthetic peptide designed to act on two hormone receptors at once: the receptor for glucagon-like peptide-1 (GLP-1), which is the target of semaglutide and liraglutide, and the receptor for glucagon. It was first reported in people in 2021 under the code IBI362, also written LY3305677, in a phase 1b trial run in China by Innovent Biologics ^[1]. The Lilly code shows where the molecule came from: it was developed by Eli Lilly and Company, with Innovent holding the rights in China ^[6].

It belongs to the same family of dual and triple agonists as tirzepatide, which acts on GIP and GLP-1 receptors, retatrutide, which acts on GIP, GLP-1 and glucagon receptors, and survodutide, which like mazdutide acts on glucagon and GLP-1 receptors. What sets mazdutide apart in September 2026 is that it is the first of the glucagon-receptor drugs to be approved as a medicine anywhere, under the brand name Xinermei in China ^[6].

Because of that approval and the trial results behind it, the mazdutide peptide is widely sold by online research suppliers outside China. Those vials are not Xinermei and are not made by Innovent or Lilly. For what the research label does and does not mean, see what research peptides are.

The GLP-1 half of the molecule does what GLP-1 drugs do: it reduces appetite and food intake, slows stomach emptying and improves insulin release after meals. The glucagon half is intended to add something different. Glucagon raises energy expenditure and drives the liver to burn fat, so a molecule that activates both receptors can, in principle, reduce calorie intake and raise calorie use at the same time. The trade-off is that glucagon also raises blood glucose, so the balance between the two activities matters, particularly in people with diabetes ^{[4] [7]}.

In the Chinese trials, this design translated into weight loss larger than that seen with the older GLP-1 drug dulaglutide. In a 28-week phase 3 comparison in people with type 2 diabetes, mazdutide 4 mg and 6 mg reduced body weight by 3.78 and 5.76 percentage points more than dulaglutide 1.5 mg, while also lowering HbA1c by 0.24 and 0.30 percentage points more ^[8]. That result is consistent with the glucagon component adding weight loss on top of GLP-1 receptor activity without costing glucose control.

Innovent has also reported effects on cardiometabolic measures in the GLORY-1 trial, describing beneficial changes in all prespecified measures such as waist circumference, blood pressure, lipids and liver fat ^[5]. As with any drug in this class, it is not yet known how much of those changes is due to weight loss itself and how much to the drug acting directly on the liver or blood vessels.

Mazdutide results have been published at every stage from phase 1 to phase 3, almost all in China. The first phase 1b trial gave 3.0 mg, 4.5 mg or 6.0 mg weekly for 12 weeks to 36 Chinese adults with overweight or obesity. Weight fell by 4.81%, 6.40% and 6.05% in the three cohorts against a 0.60% rise on placebo, and no participant stopped for safety reasons ^[1]. A follow-on cohort study pushed the dose to 9 mg and 10 mg: weight fell by 11.7% at 12 weeks on the 9 mg regimen against 1.8% on placebo, and by 9.5% at 16 weeks on the 10 mg regimen ^[2].

The phase 2 obesity trial randomised 248 adults at 20 hospitals to 3 mg, 4.5 mg, 6 mg or placebo for 24 weeks. Weight changed by −6.7%, −10.4% and −11.3% on the three doses, against +1.0% on placebo ^[3]. A separate phase 2 arm tested 9 mg in 80 adults with a BMI of at least 30 and no diabetes: weight fell by 12.78% at 24 weeks against a 1.80% rise on placebo, and 81.7% of participants lost at least 5% of their body weight, compared with none on placebo ^[12].

In type 2 diabetes, a 20-week phase 2 trial compared 3, 4.5 and 6 mg with open-label dulaglutide 1.5 mg and placebo in 250 patients. HbA1c fell by 1.41 to 1.67 percentage points on mazdutide against 1.35 on dulaglutide and a 0.03 rise on placebo, and weight fell by up to 7.1% against 2.7% on dulaglutide and 1.4% on placebo ^[4].

Outside China, the main published evidence is a US phase 2 trial by Lilly in 179 adults without diabetes, reported in 2026. Over 32 weeks, weight fell by 7.3% on a 3 to 6 mg regimen, 15.6% on 10 mg and 18.1% on 16 mg, against 0.9% on placebo, with further reductions by week 48 ^[10]. An earlier US phase 1 study of 32 adults escalated to 16 mg over 20 weeks and reported weight loss of 20.0% and 21.0% in two cohorts against 0.1% on placebo, with two-thirds to three-quarters of participants losing at least 15% ^[11]. These are small studies, and the discontinuation rate at 16 mg in the larger trial, discussed below, is the caveat.

GLORY-1 is the phase 3 trial that led to the Chinese approval. Published in the New England Journal of Medicine in 2025, it randomised 610 Chinese adults with a BMI of at least 28, or 24 to 28 with a weight-related condition, to mazdutide 4 mg, 6 mg or placebo for 48 weeks. At the primary time point of week 32, weight fell by 10.09% on 4 mg and 12.55% on 6 mg against a 0.45% rise on placebo, and 73.9%, 82.0% and 10.5% of participants respectively lost at least 5%. By week 48 the figures were −11.00%, −14.01% and +0.30%, and 35.7% of the 6 mg group had lost at least 15% ^[5]. Those results used the treatment-policy estimand, which counts everyone randomised whether or not they stayed on the drug.

GLORY-2, published in JAMA in 2026, tested a higher 9 mg dose in 461 Chinese adults with a BMI of at least 30, 16% of whom had type 2 diabetes. After 60 weeks, weight fell by 16.65% on mazdutide against 1.50% on placebo, a difference of 15.15 percentage points, and 84.3% of the mazdutide group lost at least 5% compared with 33.1% on placebo. The cost was gastrointestinal: vomiting affected 53.1% of the mazdutide group against 1.3% on placebo, nausea 46.9% against 3.2% and diarrhoea 39.4% against 6.5%, although 2.9% stopped treatment because of adverse events ^[9].

The DREAMS trials cover type 2 diabetes. DREAMS-1 randomised 320 Chinese adults whose diabetes was not controlled by diet and exercise to mazdutide 4 mg, 6 mg or placebo for 24 weeks. HbA1c fell by 1.57 and 2.15 percentage points against 0.14 on placebo, and weight by 5.61% and 7.81% against 1.26% ^[7]. DREAMS-2 randomised 731 adults on background oral diabetes drugs to mazdutide 4 mg, 6 mg or dulaglutide 1.5 mg for 28 weeks; both mazdutide doses were superior to dulaglutide on HbA1c and on weight, at the price of more gastrointestinal adverse events ^[8]. Both were published in Nature in 2026. A further phase 3 trial, DREAMS-3, is comparing mazdutide with semaglutide in people with type 2 diabetes and obesity; its design and baseline data were published in 2026 ^[13], but we found no results as of September 2026.

Taken together, the mazdutide phase 3 data as of September 2026 come from Chinese populations with lower average body weights than typical Western obesity trials: the mean weight in GLORY-1 was 87.2 kg and the mean BMI 31.1 ^[5]. Whether the same percentages hold in heavier populations is what the Lilly programme outside China is intended to show.

The trials measured weight at fixed time points rather than reporting onset. In the phase 1b study, the difference from placebo was already clear at 12 weeks, at roughly 5 to 6 percentage points ^[1]. In GLORY-1, most of the 48-week effect was present by week 32: −12.55% at week 32 and −14.01% at week 48 on 6 mg ^[5]. In GLORY-2 the weight curve was still falling at 60 weeks, when the mean loss on 9 mg reached 16.65% ^[9].

All of the trials stepped the dose up in stages over several weeks, so the early weeks are spent at lower doses than the target dose. In the phase 1b trial, for example, the 6 mg cohort started at 2 mg for four weeks, then 4 mg for four weeks, before reaching 6 mg ^[1]. The weight losses quoted above therefore include a run-in period at sub-target doses.

The doses studied are, in ascending order: 3 mg, 4.5 mg and 6 mg weekly in the phase 1b and phase 2 trials ^{[1] [3]}; 4 mg and 6 mg weekly in GLORY-1 and the DREAMS diabetes trials ^{[5] [7] [8]}; 9 mg weekly in the 9 mg phase 2 arm and in GLORY-2 ^{[9] [12]}; 10 mg in an early cohort study ^[2]; and 10 mg and 16 mg in the US phase 1 and phase 2 studies ^{[10] [11]}. Every regimen escalated over weeks. The 9 mg phase 1b cohort, for instance, gave 3 mg for weeks 1 to 4, 6 mg for weeks 5 to 8 and 9 mg for weeks 9 to 12 ^[2]. In the US phase 2 trial, the 3 to 6 mg group stayed at 3 mg from week 4 to week 32 before moving to 6 mg, specifically to test whether 3 mg and 6 mg could serve as maintenance doses ^[10].

The doses licensed in China are those from GLORY-1 and DREAMS, not the 9 mg or 16 mg regimens, which remain investigational. These figures are reported for information only and are not recommendations. There is no approved mazdutide dosage outside China, and a mazdutide dosage chart from a vendor website is not a label. Vials sold as research material have not been shown to contain what they claim, so trial doses cannot be reproduced from them. Our peptide calculator does reconstitution arithmetic, and the bacteriostatic water guide covers the diluent, but neither can correct a wrong label.

Every published mazdutide study used subcutaneous injection once a week ^{[1] [5] [9]}. Xinermei is supplied in China as a prefilled injection ^[6]. Research suppliers sell mazdutide as a freeze-dried powder for reconstitution, a form that has never been used in any trial. No oral, nasal or other route has been studied in people.

The mazdutide side effects reported in trials are the ones familiar from GLP-1 drugs, and they scale with dose. In the phase 2 obesity trial the most common were diarrhoea, nausea and upper respiratory tract infection ^[3]. In the type 2 diabetes phase 2 trial, diarrhoea affected 36%, decreased appetite 29%, nausea 23%, vomiting 14% and hypoglycaemia 10% (against 8% on placebo) ^[4]. In GLORY-1, gastrointestinal events were the most frequent and mostly mild to moderate, and only 1.5% on 4 mg and 0.5% on 6 mg stopped because of adverse events, against 1.0% on placebo ^[5].

At 9 mg the picture is harsher: in GLORY-2, more than half of participants vomited and nearly half had nausea, although 2.9% discontinued ^[9]. In the 9 mg phase 2 arm, nausea affected 50%, diarrhoea 38.3% and vomiting 36.7% ^[12]. In the US phase 2 trial, 20% of the 16 mg group stopped treatment because of adverse events, mostly gastrointestinal ^[10]. In the first phase 1b study, three participants on mazdutide had mild, symptom-free heart rhythm findings on ECG, which the authors reported without drawing a conclusion ^[1].

The published abstracts we reviewed do not report rates of hair loss, fatigue, gallbladder disease or pancreatitis for mazdutide, and no trial has been long or large enough to assess cancer risk. For licensed GLP-1 medicines, those warnings appear on the product label; the Chinese label for Xinermei is the only one that exists for mazdutide. Material bought online adds a separate layer of risk: unknown content, unknown purity and no medical supervision. The FDA has warned companies selling mazdutide labelled “for research purposes” or “not for human consumption” that were in fact selling it to consumers with dosing instructions ^[16].

Mazdutide vs retatrutide is the comparison people ask about most, because both add glucagon receptor activity. The difference is GIP: retatrutide acts on GIP, GLP-1 and glucagon receptors, mazdutide on GLP-1 and glucagon only. Neither has been compared with the other in a trial. In separate phase 2 trials, retatrutide 12 mg produced 24.2% weight loss at 48 weeks in a US population with a mean BMI around 37 ^[14], while mazdutide 6 mg produced 14.01% at 48 weeks in GLORY-1 in a Chinese population with a mean BMI of 31.1 ^[5], and mazdutide 16 mg produced 18.1% at 32 weeks in the US phase 2 trial ^[10]. Different populations, doses and durations make these numbers unsuitable for ranking the two drugs.

Mazdutide vs tirzepatide has the same limitation. Tirzepatide is a licensed medicine in the US, UK and EU whose SURMOUNT-1 trial reported 20.9% weight loss at 72 weeks on 15 mg ^[17]. Mazdutide has no trial of that length outside China, and no head-to-head trial against tirzepatide has been published. What can be said is that mazdutide is approved in China and tirzepatide is approved in many more countries; our retatrutide vs tirzepatide and tirzepatide vs semaglutide pages cover the licensed comparisons in more detail.

Survodutide is the closest relative: it too is a glucagon and GLP-1 receptor dual agonist, developed by Boehringer Ingelheim. Its phase 2 trial reported 14.9% weight loss at 46 weeks on 4.8 mg ^[15], a figure in the same range as GLORY-1. Survodutide is not approved anywhere as of September 2026, whereas mazdutide is approved in China. Our survodutide guide sets out its phase 3 results. For an overview of the whole class, see peptides for weight loss.

China’s National Medical Products Administration approved mazdutide in June 2025 for long-term weight management in adults with a BMI of at least 28, or at least 24 with a weight-related condition, and in September 2025 for glycaemic control in type 2 diabetes. It is marketed there by Innovent as Xinermei and is a prescription medicine ^[6]. This is the first approval anywhere for a drug that activates the glucagon receptor for weight management.

There is no mazdutide FDA approval. As of September 2026 mazdutide is not approved by the FDA, the UK MHRA, the European Medicines Agency or the Australian TGA. Lilly’s US phase 2 trial was published in 2026 ^[10], and any US filing would follow phase 3 trials that had not reported when we checked. The FDA lists mazdutide among the unapproved GLP-1 drugs it is concerned about and has warned sellers of “research purposes” mazdutide ^[16]; see the US legal status page and our news item on the FDA warnings to research-use GLP-1 sellers.

In the UK, mazdutide is an unlicensed medicine; see the UK legal status page. The position in Europe, Canada and Australia is the same: no marketing authorisation exists. A vial of mazdutide sold as a research product in any of these countries is not Xinermei and is not a licensed medicine, whatever the label says. Our legal status overview explains how each country treats unlicensed peptides.

The only storage instructions that exist are those on the Chinese Xinermei label, which we have not reviewed. Research material is sold as a freeze-dried powder; general practice for peptides of this kind is to keep it cold, dry and away from light and to refrigerate it once reconstituted. See how to store peptides. For comparison, licensed GLP-1 pens such as Saxenda are kept refrigerated at 2 °C to 8 °C before first use, but that label does not apply to mazdutide powder.

PepFinder does not sell mazdutide. If you are comparing research suppliers, see compare mazdutide prices, read how to read a COA, and check our list of third-party tested suppliers. A certificate of analysis for mazdutide should report a measured mass consistent with its molecular weight of about 4476 g/mol and should state the quantity in the vial, not just purity.

We track listings in the UK, the US, Canada, Australia and Europe. No published study has tested the content of research-grade mazdutide that we could find, so there is no evidence either way on whether online vials match their labels. Our guides to third-party peptide testing, spotting a fake supplier and peptide prices explained cover what to check.