Mazdutide cut body weight by about 17% in a phase 3 obesity trial in China

Mazdutide, a once-weekly injection that activates two gut-hormone receptors at once, reduced body weight by an average of 16.65% over 60 weeks in Chinese adults with obesity, against 1.50% on placebo, according to the phase 3 GLORY-2 trial published in JAMA [s1]. The between-group difference was 15.15 percentage points (95% confidence interval 13.09 to 17.22; P<0.001), placing the drug in the range of the most effective obesity medicines now in use [s1].

Mazdutide is a dual agonist of the glucagon-like peptide-1 (GLP-1) and glucagon receptors — a different pairing from tirzepatide, which combines GLP-1 with GIP [s1]. Adding glucagon-receptor activity is intended to raise energy expenditure and act on the liver, on top of the appetite suppression that GLP-1 drugs deliver. GLORY-2 is the registrational efficacy trial for the drug in obesity, and it was conducted entirely in China, where mazdutide is being developed by Innovent Biologics [s1].

What the trial did

GLORY-2 was a double-blind, placebo-controlled, phase 3 randomised trial run at 27 hospitals from December 2023 to November 2025 [s1]. It enrolled Chinese adults with obesity, defined as a body-mass index of at least 30, with or without type 2 diabetes [s1]. Participants were randomised 2:1 to mazdutide 9 mg once weekly by subcutaneous injection or placebo, each as an adjunct to a reduced-calorie diet and increased physical activity, for 60 weeks [s1].

A total of 461 participants received treatment and were analysed — 307 on mazdutide and 154 on placebo [s1]. They were, on average, relatively young and substantially above the obesity threshold: mean age 33.9 years, mean body weight 94.0 kg, mean BMI 34.3, with 64.0% women and 16.1% carrying a diagnosis of type 2 diabetes [s1]. The co-primary outcomes were the percentage change in body weight and the proportion of participants losing at least 5% of their weight, both at week 60 [s1].

What it found

On the first co-primary endpoint, mean weight change was −16.65% (95% CI −18.19 to −15.12) with mazdutide versus −1.50% (95% CI −3.43 to 0.43) with placebo [s1]. On the second, 84.3% of the mazdutide group lost at least 5% of their body weight, against 33.1% on placebo — a difference of 51.6 percentage points (95% CI 43.0 to 60.1; P<0.001) [s1].

The tolerability profile was the familiar one for this drug class, and pronounced. Vomiting affected 53.1% of the mazdutide group versus 1.3% on placebo, nausea 46.9% versus 3.2%, and diarrhoea 39.4% versus 6.5% [s1]. Most events were mild to moderate, and adverse events led 2.9% of mazdutide participants to stop treatment, compared with none on placebo [s1].

How to read it

The efficacy is genuinely large. A roughly 17% average weight loss over about 14 months is competitive with the strongest agents in the field, and the 84.3% who reached the 5% threshold is the kind of response rate that reshapes clinical expectations [s1]. But three qualifications belong alongside it.

First, gastrointestinal side effects were near-universal at this dose — more than half the drug group vomited — and while few people quit the trial, real-world persistence is often lower than in a supervised study [s1]. Second, the trial population was young, with a mean age of 33.9 years, and predominantly without diabetes, so the results speak most directly to younger adults with obesity and less certainly to older patients or those with more metabolic complications [s1]. Third, GLORY-2 measured weight and short-term safety over 60 weeks; it was not designed to show whether the weight loss translates into fewer heart attacks, strokes or deaths — the outcomes that ultimately justify long-term use of an obesity drug [s1].

An accompanying JAMA editorial places mazdutide alongside the oral agent orforglipron as part of a widening set of options while cautioning that head-to-head and cardiovascular-outcome data remain the open questions for the class [s2].

Why it matters

Mazdutide's glucagon-plus-GLP-1 design is one of several attempts to push past the GLP-1 ceiling by recruiting a second hormone pathway, and GLORY-2 is the clearest efficacy read yet for this particular combination. It also underscores how much of the obesity-drug pipeline is now being tested first, and sometimes only, in single national populations — here, China — which shapes both who the evidence applies to and where the drug reaches patients first.

The result can be read against the drug's earlier US phase 2 obesity trial, which tested a range of doses in a different population, and against the broader network meta-analysis ranking obesity drugs by effect. A separate dual agonist with a glucagon component, survodutide, is covered in the context of its phase 3 MASLD trial.

What to watch

The open questions are the ones GLORY-2 could not answer: how mazdutide compares directly with tirzepatide and semaglutide, whether its glucagon activity delivers the metabolic benefits its design promises, and whether a cardiovascular-outcomes trial confirms that the weight loss prevents disease rather than merely registering on the scale [s1][s2]. Regulatory reach outside China, and how the heavy early gastrointestinal burden affects who stays on the drug, will shape its real-world place.

This article describes clinical-trial research and drug dosing and is not medical advice. Decisions about obesity treatment are for patients and their treating clinicians.

Sources

• Treatment With 9-mg Mazdutide for Weight Reduction in Chinese Adults With Obesity: The GLORY-2 Randomized Clinical Trial — JAMA, 4 August 2026
• Mazdutide and Orforglipron—New Evidence in Obesity and Diabetes — JAMA, 4 August 2026 (editorial)