Mazdutide Research Guide: Mechanism, Trials and Regulatory Status

Oxyntomodulin, the hormone mazdutide is modelled on, is released from the gut after eating and signals through both the GLP-1 receptor and the glucagon receptor. Activating the GLP-1 receptor slows gastric emptying, increases insulin release and reduces appetite; activating the glucagon receptor is linked to higher energy expenditure and hepatic fat oxidation, an effect so far demonstrated mainly in animal models. Mazdutide was designed to engage both receptors at once rather than the GLP-1 receptor alone.^[8][1]

Before it reached human trials, mazdutide was shown to bind potently to both human and mouse GLP-1 and glucagon receptors in vitro, and to improve glucose control in mice. That preclinical binding and rodent-metabolism work underpins the receptor-engagement claims used throughout its clinical programme — it is pharmacology, not a guarantee of the same effect size in every person.^[1]

Because glucagon-receptor activity raises blood glucose on its own, it is only really usable pharmacologically alongside GLP-1 receptor activity, which offsets that effect. Mazdutide, survodutide and retatrutide all follow this logic, though the receptor mix differs: mazdutide and survodutide are dual GLP-1/glucagon agonists, while retatrutide adds a third receptor, GIP. The two dual agonists and the triple agonist are compared in detail in a dedicated article.^[8]

Mazdutide's first published human data come from a placebo-controlled, dose-escalation phase 1b trial in Chinese adults with overweight (BMI of at least 24, with hyperphagia or at least one weight-related comorbidity) or obesity (BMI of at least 28), run at six centres in China. Twenty-four participants were randomised 2:1 to once-weekly mazdutide or placebo across three ascending-dose cohorts (up to 3.0, 4.5 or 6.0 mg) for 12 weeks. Mean body weight fell by 4.81%, 6.40% and 6.05% across the three cohorts, against a 0.60% rise with placebo (p<0.0001 for every comparison), and 54.2% of participants receiving mazdutide reached at least 5% weight loss, against none on placebo.^[1]

The pivotal phase 3 trial, GLORY-1, published in the New England Journal of Medicine in 2025, followed 610 Chinese adults with a BMI of at least 28, or 24 to 28 with a weight-related condition, for 48 weeks on weekly mazdutide at 4 or 6 mg or placebo. Mean body weight fell by 11.00% and 14.01% on the two doses, against a 0.30% rise with placebo, and 35.7% and 49.5% of participants reached a reduction of at least 15%, against 2.0%.^[3]

GLORY-2, published in JAMA in 2026, tested a higher 9 mg dose in 461 Chinese adults with a BMI of at least 30 over 60 weeks. Body weight fell by 16.65%, against 1.50% with placebo. Gastrointestinal effects were frequent at this dose: vomiting in 53.1% of the mazdutide group, nausea in 46.9% and diarrhoea in 39.4%, mostly mild to moderate.^[4]

Outside China, a 179-person phase 2 trial in the US, published in The Lancet Diabetes & Endocrinology in 2026, reported 32-week weight reductions of 7.3%, 15.6% and 18.1% across its 3–6 mg, 10 mg and 16 mg groups, against 0.9% with placebo. Twenty percent of the 16 mg group stopped treatment because of adverse events — the clearest signal so far that higher doses trade additional weight loss for a harder tolerability profile.^[5]

Two phase 3 trials in adults with type 2 diabetes, both published in Nature in 2026, tested mazdutide over six to seven months. DREAMS-1 reported HbA1c reductions against placebo at 24 weeks. DREAMS-2 reported that mazdutide was superior to dulaglutide 1.5 mg on glycaemic control at 28 weeks, with greater weight loss than dulaglutide in the same trial.^[6][7]

The type 2 diabetes approval in China, in September 2025, followed this second trial programme, three months after the initial weight-management approval.^[2]

Mazdutide is also under early clinical evaluation for metabolic dysfunction-associated fatty liver disease (MASLD), obstructive sleep apnoea and alcohol use disorder, alongside its approved weight-management and diabetes uses. The most detailed published MASLD data so far are preclinical: a 2026 study induced MASLD in mice with a high-fat diet and, separately, in cultured human hepatocytes exposed to free fatty acids, then treated both with mazdutide. Treated mice and cells showed less hepatic fat accumulation, lower liver-injury markers and less inflammation, with the authors proposing a mechanism involving endoplasmic-reticulum stress and NF-κB signalling. This is mouse and cell-culture evidence for a mechanism, not a result from a person.^[2][10]

In obstructive sleep apnoea, mazdutide is in an ongoing phase 3 trial (GLORY-OSA) in Chinese adults with moderate-to-severe OSA and a BMI of at least 28, registered to compare mazdutide 9 mg against placebo on the change in apnoea-hypopnoea index — the number of breathing interruptions per hour of sleep — at 48 weeks. As of this article's publication, the trial is running and no results have been reported.^[11]

In alcohol use disorder, Eli Lilly is running a placebo-controlled phase 2 proof-of-concept trial of mazdutide, measuring alcohol-related behaviour with the Timeline Followback method from baseline to 28 weeks. Like the sleep-apnoea trial, it has not yet reported results.^[12]

Across every published mazdutide trial, gastrointestinal effects are the dominant tolerability signal: decreased appetite, nausea, vomiting and diarrhoea, generally mild to moderate and more frequent at higher doses and in the days immediately after each weekly injection. In the first-in-human phase 1b trial, no participant discontinued for safety reasons, there was no hypoglycaemia, and no serious adverse event occurred. In the 16 mg arm of the US phase 2 trial, by contrast, 20% of participants stopped treatment because of adverse events — evidence that tolerability, not just efficacy, changes with dose.^[1][5]

Heart rate is the signal reviewers are watching most closely with any glucagon-receptor co-agonist, mazdutide included. A 2026 review found that mazdutide and survodutide generally raised heart rate to a similar extent as GLP-1-receptor-only agonists, but noted that at least one other dual agonist in the same class was discontinued partly for large heart-rate increases and QT prolongation, and concluded that cardiovascular effects need to be clarified compound by compound in the trials still running.^[9]

Mazdutide is a dual agonist: it activates the GLP-1 and glucagon receptors. Survodutide (BI 456906) is the other dual agonist with published phase 3 data. Retatrutide goes further, adding a third receptor, GIP, which makes it a triple agonist — the structural difference behind its own trial programme and behind the comparison readers most often search for.^[8]

That comparison — the receptor differences, the head-to-head data set out side by side, and why the two development programmes cannot be ranked against each other — is covered in full in a dedicated article rather than repeated here. Peptyds supplies retatrutide as a research peptide; it does not supply mazdutide or survodutide.

As of September 2026, mazdutide's only regulatory approvals are the two granted in China in 2025. The European Medicines Agency's database of authorised medicines lists no mazdutide product, and there is no EPAR for it. In the United States, published clinical work is limited to the phase 1b and phase 2 trials described above; mazdutide has not reached a phase 3 readout or a regulatory filing there.^[13][2][5]

Peptyds does not supply mazdutide. It supplies retatrutide, tirzepatide and semaglutide as lyophilised research peptides for in-vitro laboratory work only, each with batch documentation described on the quality page. None of these research products is a medicine, and none is intended for human use; nothing in this article is instruction for personal use of mazdutide, which in any case Peptyds does not sell.