Mazdutide: A Literature Course on What the Studies Report

This six-module course summarises the peer-reviewed literature on mazdutide without recommending any use of it. This page is for educational purposes only and is not medical advice; consult a licensed physician about any medical or treatment question. Every dose, endpoint and adverse event below is linked to the paper that reported it, and each module closes with the limits of that evidence.

Module 1 — What mazdutide is and how it has been studied

Mazdutide is a synthetic peptide designed to activate two receptors at once: the glucagon-like peptide-1 receptor (GLP-1R) and the glucagon receptor (GCGR). In the published record it also appears under the development codes IBI362 and LY3305677, and the earliest clinical reports used those names when describing a GLP-1 and glucagon receptor dual agonist administered subcutaneously to Chinese patients with type 2 diabetes (phase 1b trial). The molecule is described in the literature as an oxyntomodulin-based analogue, meaning its sequence derives from a natural gut peptide that intrinsically engages both receptors rather than the GLP-1 receptor alone.

A 2025 drug-approval review in Drugs summarised the development history, describing mazdutide as a once-weekly GLP-1R/GCGR dual agonist developed in China and reaching its first regulatory approval in 2025 (Mazdutide: First Approval). That review is the most compact orientation to the compound's lineage and indications.

Clinically, the peptide has been investigated in two broad populations: adults with overweight or obesity, and adults with type 2 diabetes. The trial programme progressed from multiple-ascending-dose phase 1b work through randomised phase 2 studies to phase 3 comparisons against placebo and against an active GLP-1 comparator. A separate preclinical strand examined a diabetes-related cognitive endpoint in an animal model (multi-omics study).

Forms described in the literature

• Route: subcutaneous injection in the clinical trials (phase 1b, type 2 diabetes).
• Schedule: once weekly across the phase 2 and phase 3 programme (once-weekly phase 3 obesity trial).
• Dose strengths studied: 3 mg, 4.5 mg and 6 mg in phase 2 obesity work (phase 2 randomised trial); 9 mg and 10 mg in a phase 1b multiple-ascending-dose study (phase 1b, overweight or obesity); and 9 mg in a later randomised clinical trial (GLORY-2).

Limits of the evidence in Module 1

The clinical literature summarised here was generated overwhelmingly in Chinese adult populations, so generalisability to other ancestries, to adolescents and to older adults was not established by these reports. Names and codes in older papers (IBI362, LY3305677) can make the same molecule look like several different agents in database searches.

Module 2 — Mechanism as described in the literature

The mechanistic framing in the published papers is consistent: mazdutide is characterised as a dual agonist that engages GLP-1R and GCGR simultaneously, and the authors of a 2025 mechanistic paper described it explicitly as "a dual agonist targeting GLP-1R and GCGR" (EBioMedicine, 2025).

The GLP-1 receptor arm

GLP-1 receptor activation is the better-characterised half of the mechanism and underlies the glucose-lowering results seen when mazdutide was tested in type 2 diabetes; researchers reported reductions in glycated haemoglobin relative to placebo in a randomised, double-blind phase 2 trial (Diabetes Care, 2024). Phase 3 work compared the peptide with dulaglutide, a selective GLP-1 receptor agonist, which positions the GLP-1 arm as the shared component between the two drugs (mazdutide versus dulaglutide).

The glucagon receptor arm

The glucagon component is what distinguishes mazdutide from single-receptor GLP-1 agonists in the literature. The phase 1b report in Chinese patients with type 2 diabetes framed IBI362 as a GLP-1 and glucagon receptor dual agonist and evaluated metabolic effects on that basis (Nature Communications, 2022). The 2025 approval review described the compound in the same dual-receptor terms when summarising its indications (Drugs, 2025).

A preclinical mechanism paper

Beyond metabolic endpoints, one 2025 study used multi-omics analysis in a diabetes model and reported that mazdutide mitigated diabetes-associated cognitive dysfunction, offering mechanistic hypotheses rather than a clinical claim (EBioMedicine, 2025).

Limits of the evidence in Module 2

Receptor pharmacology in these papers is stated as a property of the molecule; the trials measured downstream outcomes such as weight and HbA1c rather than dissecting how much of each result came from GLP-1R versus GCGR activation. The cognitive-dysfunction work was preclinical and does not establish any human neurological effect.

Module 3 — Reported outcomes by study

The table below maps the verified clinical literature. Every entry links to the study that reported it.

Two features of the outcome literature are worth naming. First, the endpoints repeat: percentage change in body weight in the obesity trials, and HbA1c change in the diabetes trials, with body weight as a secondary endpoint there. Second, the dose range widened over time, from 3–6 mg in phase 2 obesity work (phase 2, 2023) to 9 mg and 10 mg in early dose-ranging (phase 1b, 2022) and a dedicated 9-mg randomised trial (GLORY-2, 2026).

Limits of the evidence in Module 3

Group averages are not individual predictions, and none of these trials was designed to promise a result for any particular person. Trial durations were measured in weeks to about a year rather than years, so durability after treatment stopped, and hard outcomes such as cardiovascular events, were not the endpoints of the studies cited above. The pooled analysis inherits the limitations of the trials it combined (meta-analysis, 2024).

Module 4 — Mazdutide Side Effects: What Studies Report

Adverse events in the mazdutide literature cluster in the gastrointestinal tract, which is the pattern described for incretin-based agents generally. The phase 2 trial in Chinese overweight adults and adults with obesity assessed safety alongside weight outcomes and reported that gastrointestinal events were the most common treatment-emergent findings (phase 2, 2023). The phase 2 diabetes trial likewise reported safety as a co-primary concern across the 3 mg, 4.5 mg and 6 mg groups (Diabetes Care, 2024).

Dose-ranging work at the top of the studied range is the most informative source on tolerability. The multiple-ascending-dose phase 1b trial was explicitly framed as a safety and efficacy evaluation of 9 mg and 10 mg in Chinese adults with overweight or obesity (EClinicalMedicine, 2022), and a later high-dose phase 1 trial examined weight change at higher exposures (high-dose phase 1, 2025). The phase 1b study in patients with type 2 diabetes reported safety findings for the dual agonist in that population (Nature Communications, 2022).

At the phase 3 stage, the once-weekly obesity trial reported safety outcomes alongside its weight endpoint (NEJM, 2025), the 9-mg randomised trial reported adverse events in adults with obesity (JAMA, 2026), and the two 2026 diabetes trials reported safety against placebo and against dulaglutide respectively (versus placebo; versus dulaglutide). The 2024 systematic review and meta-analysis pooled efficacy and safety across randomised controlled trials in diabetic and non-diabetic participants, which is the closest thing in this set to an aggregate tolerability picture (Frontiers in Endocrinology, 2024). The 2025 approval review summarised the adverse-event profile as part of its regulatory overview (Drugs, 2025).

Limits of the evidence in Module 4

Trial safety data describe monitored volunteers who met eligibility criteria and were followed for a defined period; they do not capture rare events, long-term risks, drug interactions outside the protocols, or outcomes in people excluded from enrolment. Readers who want event-by-event frequencies should consult the individual publications rather than rely on a summary, and any personal risk question belongs with a licensed clinician.

Module 5 — Pharmacokinetics where data exist

The pharmacokinetic story in the verified literature is largely structural rather than numerical. The consistent signal is dosing interval: the phase 3 obesity trial was titled and designed around once-weekly administration (NEJM, 2025), and the phase 2 obesity and diabetes trials also used weekly subcutaneous dosing at 3 mg, 4.5 mg and 6 mg (phase 2 obesity; phase 2 diabetes). A weekly schedule implies an exposure profile engineered for extended circulation, which is how the papers describe the agent's clinical use.

Dose escalation was studied formally. The multiple-ascending-dose phase 1b design tested successively higher weekly doses up to 9 mg and 10 mg (EClinicalMedicine, 2022), and a separate high-dose phase 1 trial extended that work while measuring body weight (Diabetes, Obesity and Metabolism, 2025). The first-in-patient phase 1b study in type 2 diabetes provided the earliest human exposure data for the molecule (Nature Communications, 2022).

Limits of the evidence in Module 5

No half-life, clearance, bioavailability or time-to-peak figure is quoted on this page, because the verified sources summarised here do not supply those values in the material available. Phase 1 pharmacokinetics were also generated in specific Chinese cohorts, and absorption and exposure can differ with body composition, injection technique and formulation. Readers needing numeric pharmacokinetic parameters should go to the primary phase 1 publications and any official prescribing information.

Module 6 — Regulatory status, stated factually

Mazdutide received its first regulatory approval in 2025, a milestone documented in the Drugs "First Approval" review, which described the agent as a once-weekly GLP-1R/GCGR dual agonist approved in China and summarised the indications and development programme behind that decision (Mazdutide: First Approval, 2025). The clinical dossier supporting that status was built on trials conducted in Chinese adults with obesity or overweight (NEJM, 2025) and in Chinese adults with type 2 diabetes (Nature, 2026).

Several general regulatory points follow from that, stated as facts rather than guidance:

• Approval is jurisdictional. An approval granted by one national regulator does not constitute approval elsewhere; marketing authorisation in the United States or European Union would require separate review by the FDA or EMA.
• "Research use only" (RUO) material is not a medicine. Peptides labelled RUO are supplied for laboratory work, are not manufactured or released as human drug products, and are not approved for administration to people. RUO labelling carries no assurance of identity, purity, sterility or potency for human use.
• Compounding is separately regulated. In the United States, compounded preparations are not FDA-approved products; federal rules restrict compounding of drugs that are essentially copies of commercially available approved products, and compounding of peptides depends on the substance's regulatory category. These rules differ by country and change over time.

This section describes published regulatory facts and general rules; it is not legal advice, and it is not medical advice.

Limits of the evidence in Module 6

Regulatory status is a moving target: approvals, label indications and compounding policy can change after any paper is published, so a 2025 review captures a snapshot rather than a permanent state. The verified literature also does not describe product-quality standards for non-pharmaceutical material.

What the studies did not test

Reading the whole set together, the gaps are as important as the findings:

1. Long-term outcomes. The cited trials measured weight, HbA1c and adverse events over defined trial periods; they did not report multi-year cardiovascular, renal or mortality outcomes.
2. Populations outside the enrolled cohorts. The clinical programme summarised here was conducted in Chinese adults (NEJM, 2025; Diabetes Care, 2024), leaving other ancestries, pregnancy, paediatric and many comorbid groups untested.
3. What happens after discontinuation. None of the cited reports was framed as a study of weight or glycaemic trajectory after treatment stopped.
4. Non-trial use. No cited study evaluated unsupervised administration, self-selected doses, combination with other peptides, or material obtained outside a regulated supply chain.
5. Cognitive endpoints in humans. The cognitive-dysfunction finding was reported in a preclinical model with multi-omics analysis (EBioMedicine, 2025), not in a clinical trial.

Mazdutide's literature is unusually concentrated — one development programme, one main geography, two indications — which makes it easy to read but also easy to over-extend. Any question about personal suitability, risk or monitoring is a question for a licensed physician, not for a summary page.

References

• Once-Weekly Mazdutide in Chinese Adults with Obesity or Overweight (The New England Journal of Medicine, 2025)
• Mazdutide: First Approval (Drugs, 2025)
• Mazdutide, a dual agonist targeting GLP-1R and GCGR, mitigates diabetes-associated cognitive dysfunction: mechanistic insights from multi-omics analysis (EBioMedicine, 2025)
• Efficacy and Safety of Mazdutide in Chinese Patients With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Phase 2 Trial (Diabetes Care, 2024)
• Mazdutide versus dulaglutide in Chinese adults with type 2 diabetes (Nature, 2026)
• A phase 2 randomised controlled trial of mazdutide in Chinese overweight adults or adults with obesity (Nature Communications, 2023)
• Mazdutide versus placebo in Chinese adults with type 2 diabetes (Nature, 2026)
• Safety and efficacy of a GLP-1 and glucagon receptor dual agonist mazdutide (IBI362) 9 mg and 10 mg in Chinese adults with overweight or obesity: A randomised, placebo-controlled, multiple-ascending-dose phase 1b trial (EClinicalMedicine, 2022)
• Efficacy and safety of Mazdutide on weight loss among diabetic and non-diabetic patients: a systematic review and meta-analysis of randomized controlled trials (Frontiers in Endocrinology, 2024)
• Mazdutide reduces body weight in adults with overweight or obesity: A high-dose Phase 1 trial (Diabetes, Obesity & Metabolism, 2025)
• A phase 1b randomised controlled trial of a glucagon-like peptide-1 and glucagon receptor dual agonist IBI362 (LY3305677) in Chinese patients with type 2 diabetes (Nature Communications, 2022)
• Treatment With 9-mg Mazdutide for Weight Reduction in Chinese Adults With Obesity: The GLORY-2 Randomized Clinical Trial (JAMA, 2026)