Mazdutide (code names IBI362 and LY3305677) is a once-weekly injectable peptide that activates two hormone receptors: the glucagon-like peptide-1 (GLP-1) receptor and the glucagon receptor. It is modeled on oxyntomodulin, a gut hormone that naturally acts on both. It is being developed by Eli Lilly together with Innovent Biologics, which holds an exclusive license from Lilly for China and ran most of the published trials.
The single most important fact: mazdutide’s approvals are in China. China’s drug regulator (NMPA) approved it in June 2025 for long-term weight management, under the brand name Xinermei, and in September 2025 for blood-sugar control in type 2 diabetes (Shirley, Drugs 2025). It is not approved by the FDA. Almost all efficacy data come from Chinese adults, and the FDA has treated “research peptide” mazdutide sold online as an unapproved new drug.
This page summarizes what the published clinical trials, company trial disclosures and regulators report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Drug class | Dual GLP-1 and glucagon receptor agonist; long-acting oxyntomodulin analog |
| Developer / codes | Eli Lilly (LY3305677); Innovent Biologics in China (IBI362) |
| Brand / approval | Xinermei (China, NMPA): weight management June 2025, type 2 diabetes September 2025; not FDA-approved |
| Route | Subcutaneous injection once weekly |
| Doses studied | Phase 3 in China: 4, 6 and 9 mg/week; US trials: up to 16 mg/week |
| Half-life | Wide range after the first dose: 151–404 h (6.3–16.8 days) in adults with obesity; peak level at a median of about 72 h |
| Molecular formula | C207H317N45O65, about 4,476 g/mol (PubChem) |
| US controlled-substance status | Not listed in DEA Schedule III (21 CFR 1308.13) |
| WADA status | Not named on the 2026 List |
What it is
Oxyntomodulin is a hormone released by the gut after meals that activates both the GLP-1 receptor and the glucagon receptor. The GLP-1 receptor mainly reduces appetite, and the glucagon receptor can raise energy expenditure. Mazdutide is a synthetic peptide analog of oxyntomodulin with a fatty-acyl side chain (a fat-like chain) added to extend its half-life (Ji et al., EClinicalMedicine 2021). PubChem lists its formula as C207H317N45O65 (PubChem).
The developers’ preclinical work, summarized in the first trial report, found the following in mice (Ji et al., EClinicalMedicine 2021):
- it bound tightly to both human and mouse GLP-1 and glucagon receptors in lab tests;
- it still lowered body weight in mice lacking either the glucagon receptor or the GLP-1 receptor, suggesting both receptors contribute;
- it raised energy expenditure, which semaglutide did not.
These are animal findings. Whether the glucagon arm adds meaningful energy expenditure in people has not been settled by the human trials below, which measured weight, not energy expenditure.
How it compares with related drugs
| Drug | Receptors activated | Library page |
|---|---|---|
| Semaglutide | GLP-1 | Semaglutide |
| Tirzepatide | GIP and GLP-1 | Tirzepatide |
| Mazdutide | GLP-1 and glucagon | This page |
| Survodutide | GLP-1 and glucagon | Survodutide |
| Retatrutide | GIP, GLP-1 and glucagon | Retatrutide |
Mazdutide and survodutide belong to the same dual GLP-1/glucagon class. Retatrutide adds the glucagon component on top of tirzepatide’s two targets.
Pharmacokinetics
The human pharmacokinetic data come from two small phase 1b trials in China that measured drug levels after the first dose.
| Measure | Adults with overweight or obesity (n = 24 on drug) | Adults with type 2 diabetes |
|---|---|---|
| Time to peak level | Median 72 h (range 11.8–120 h) | Median about 72 h (range 23.3–144.2 h) |
| Half-life | 150.9–403.5 h (6.3–16.8 days) | 147.3–673.3 h (6.1–28.1 days) |
| Anti-drug antibodies | 2 participants | 16.7% on mazdutide vs 8.3% on placebo; no neutralizing antibodies |
| Source | Ji et al., EClinicalMedicine 2021 | Jiang et al., Nat Commun 2022 |
Absorption is slow, and levels then decline over several weeks. The authors concluded that this profile supports once-weekly injection. In the larger phase 2 obesity trial, anti-mazdutide antibodies developed in 22.6–32.8% of participants, rising with dose (Ji et al., Nat Commun 2023).
Regulatory status
- China. Approved in June 2025 for long-term weight management in adults with a BMI of 28 or higher, or a BMI of 24 or higher plus at least one weight-related condition, together with diet and exercise. Approved in September 2025 for blood-sugar control in adults with type 2 diabetes (Shirley, Drugs 2025). These BMI cutoffs follow Chinese definitions of overweight and obesity. Innovent states that the diabetes approval covers use alone and in combination with metformin, sulfonylureas or SGLT2 inhibitors (Innovent press release, October 2025).
- United States. Not approved. Lilly has run phase 1 and phase 2 trials in the US (Bhattachar et al., Diabetes Obes Metab 2025; Hsia et al., Lancet Diabetes Endocrinol 2026).
- FDA enforcement. FDA warning letters have named “Mazdutide” products sold by online peptide vendors as “unapproved new drugs.” The agency stated that “research use only” labeling did not change this, because the sellers’ websites showed the products were intended for human use (FDA warning letter to Summit Research Peptides, December 10, 2024).
- Controlled substances. Mazdutide is a peptide, not a steroid, and is not among the anabolic steroids listed in Schedule III (21 CFR 1308.13).
What the research shows
Unless stated, the trials below were funded by Innovent and enrolled Chinese adults. Results are mean changes from baseline.
Obesity or overweight without diabetes: GLORY-1
GLORY-1, the phase 3 trial behind the Chinese weight-management approval, randomized 610 adults (mean weight 87.2 kg, mean BMI 31.1) to 4 mg, 6 mg or placebo weekly for 48 weeks (Ji et al., NEJM 2025):
| Outcome | Placebo | 4 mg | 6 mg |
|---|---|---|---|
| Weight change at 32 weeks (95% CI) | +0.45% (−0.61 to 1.52) | −10.09% (−11.15 to −9.04) | −12.55% (−13.64 to −11.45) |
| Lost ≥5% at 32 weeks | 10.5% | 73.9% | 82.0% |
| Weight change at 48 weeks (95% CI) | +0.30% (−0.98 to 1.58) | −11.00% (−12.27 to −9.73) | −14.01% (−15.36 to −12.66) |
| Lost ≥15% at 48 weeks | 2.0% | 35.7% | 49.5% |
| Stopped treatment due to adverse events | 1.0% | 1.5% | 0.5% |
These figures use the “treatment-policy” estimand, which counts everyone regardless of whether they stopped the drug. Innovent’s conference disclosure of the same trial reported, at 48 weeks and pooled across both doses versus placebo, falls in systolic blood pressure (−9.21 vs −2.46 mmHg), triglycerides, LDL cholesterol, serum uric acid and the liver enzyme ALT (Innovent press release, June 2024). In an exploratory analysis of participants with liver fat of 10% or more on MRI, liver fat fell by an average of 80.2% on 6 mg versus 5.3% on placebo. These secondary figures come from the company release, not the peer-reviewed paper.
Higher dose in obesity: GLORY-2
GLORY-2 tested 9 mg/week against placebo for 60 weeks in 461 adults with a BMI of 30 or higher (mean 34.3; 16.1% had type 2 diabetes) (Gao et al., JAMA 2026):
| Outcome | Placebo (n = 154) | Mazdutide 9 mg (n = 307) |
|---|---|---|
| Weight change at 60 weeks | −1.50% | −16.65% |
| Difference vs placebo (95% CI) | — | −15.15% (−17.22 to −13.09) |
| Lost ≥5% | 33.1% | 84.3% |
| Vomiting | 1.3% | 53.1% |
| Nausea | 3.2% | 46.9% |
| Diarrhea | 6.5% | 39.4% |
| Stopped treatment due to adverse events | 0% | 2.9% |
A smaller 24-week phase 2 trial of 9 mg in 80 adults with a BMI of 30 or higher reported −12.78% versus +1.80% on placebo (Ji et al., Med 2026).
US trials in non-Chinese populations
Lilly has tested higher doses in the US, all in adults without diabetes:
| Trial | Design | Weight change |
|---|---|---|
| Phase 1 (Bhattachar et al., Diabetes Obes Metab 2025) | 32 adults; escalation to 16 mg vs placebo; 20 weeks | −20.0% and −21.0% (two escalation cohorts) vs −0.1% on placebo |
| Phase 2 (Hsia et al., Lancet Diabetes Endocrinol 2026) | 179 adults at 24 US centers; 3–6 mg, 10 mg or 16 mg vs placebo; 48 weeks | At 32 weeks: −7.3% (3 mg), −15.6% (10 mg), −18.1% (16 mg) vs −0.9% on placebo |
In the phase 2 trial, 20% of people on 16 mg stopped treatment because of adverse events, mainly gastrointestinal. Its weight figures use the “efficacy” estimand, which assumes people kept taking the drug, so they are not directly comparable with GLORY-1’s treatment-policy figures.
Type 2 diabetes: DREAMS-1 and DREAMS-2
| Trial | Design | HbA1c change | Weight change |
|---|---|---|---|
| DREAMS-1 (Zhu et al., Nature 2026) | 320 adults on diet and exercise alone; 4 mg, 6 mg or placebo; 24 weeks | −1.57% (4 mg), −2.15% (6 mg) vs −0.14% on placebo | −5.61% (4 mg), −7.81% (6 mg) vs −1.26% on placebo |
| DREAMS-2 (Guo et al., Nature 2026) | 731 adults on oral diabetes drugs; 4 mg, 6 mg or dulaglutide 1.5 mg; 28 weeks | 0.24 (4 mg) and 0.30 (6 mg) percentage points more than dulaglutide | 3.78 (4 mg) and 5.76 (6 mg) percentage points more than dulaglutide |
HbA1c is the average blood sugar over the past 2–3 months. Dulaglutide is a once-weekly GLP-1 receptor agonist. In DREAMS-2, gastrointestinal adverse events were more frequent on mazdutide than on dulaglutide.
Head to head with semaglutide: DREAMS-3
DREAMS-3 was an open-label (unblinded) phase 3 trial that randomized 349 Chinese adults with type 2 diabetes and obesity (mean BMI 33.0) to mazdutide 6 mg or semaglutide 1 mg weekly for 32 weeks (Luo et al., Contemp Clin Trials 2026). Innovent reported these topline results (Innovent press release, October 2025):
| Outcome at 32 weeks | Semaglutide 1 mg | Mazdutide 6 mg |
|---|---|---|
| Reached HbA1c below 7.0% and ≥10% weight loss (primary endpoint) | 21.0% | 48.0% |
| HbA1c change | −1.84% | −2.03% |
| Weight change | −6.00% | −10.29% |
These are company-reported topline results, not yet a peer-reviewed paper, and the trial was unblinded. The comparison used semaglutide at 1 mg weekly. No published trial has compared mazdutide head to head with tirzepatide or retatrutide.
Body composition
Mazdutide is not an anabolic agent, and no trial has studied it in lean or resistance-trained people. In the phase 2 obesity trial, only 22 participants had usable DXA scans (a low-dose X-ray that measures fat and lean mass). With all doses they lost more fat than lean mass in kilograms, and visceral (abdominal organ) fat fell with dose (Ji et al., Nat Commun 2023). The authors called these data limited and preliminary. Part of the weight lost is still lean tissue.
Evidence summaries
A 2026 meta-analysis of nine randomized trials (2,292 participants, mostly Chinese) found dose-dependent falls in weight and HbA1c, along with improvements in waist size, lipids, liver enzymes and uric acid (Kamrul-Hasan et al., Diabetes Obes Metab 2026). It rated the certainty of the weight-loss evidence in people without diabetes as very low, because of large differences between trials and few trials. Gastrointestinal adverse events were more frequent with mazdutide, while serious adverse events and discontinuations were similar to comparators.
Side effects and risks
This section relies on published trial data. Trials have lasted up to 60 weeks, and no cardiovascular outcomes trial has been published.
Gastrointestinal effects
Nausea, vomiting and diarrhea are the most common adverse events. They rise with dose and are most frequent during dose escalation (Ji et al., Nat Commun 2023). In that 24-week phase 2 trial:
| Adverse event | Placebo | 3 mg | 4.5 mg | 6 mg |
|---|---|---|---|---|
| Nausea | 4.8% | 21.0% | 23.8% | 41.0% |
| Diarrhea | 14.5% | 19.4% | 30.2% | 31.1% |
| Vomiting | 3.2% | 12.9% | 20.6% | 27.9% |
| Decreased appetite | 8.1% | 9.7% | 15.9% | 29.5% |
| Serious adverse events | 0% | 1.6% | 6.3% | 6.6% |
At 9 mg in GLORY-2, about half of participants reported vomiting or nausea (see the table above). Most events were mild to moderate.
Heart rate and heart rhythm
Because glucagon stimulates the heart, trial investigators expected a larger heart-rate rise with GLP-1/glucagon dual agonists than with GLP-1 drugs alone. In the phase 2 obesity trial, heart rate at 24 weeks had risen by 5.82, 5.38 and 8.75 beats per minute on 3, 4.5 and 6 mg, versus 4.81 on placebo, and returned to normal after treatment stopped (Ji et al., Nat Commun 2023). Electrocardiogram findings such as sinus tachycardia were mild, asymptomatic and not more common than on placebo. In GLORY-1, Innovent reported a mean heart-rate change of 1.6 beats per minute on both doses at 48 weeks (Innovent press release, June 2024). In the phase 1b diabetes trial, two people on 6 mg had a concurrent rise in blood pressure and heart rate and developed first-degree heart block (a mild delay in electrical conduction) (Jiang et al., Nat Commun 2022).
Pancreas and thyroid
In the phase 2 obesity trial, two participants on mazdutide had lipase (a pancreatic enzyme) rise above three times the upper limit of normal, but no pancreatitis was suspected and no participant had a calcitonin level (a thyroid C-cell marker) of 20 ng/L or higher (Ji et al., Nat Commun 2023). Trials excluded people with a history of pancreatitis, gallbladder disease, thyroid C-cell cancer or multiple endocrine neoplasia type 2A or 2B, so its safety in those groups is unknown.
Who it has not been studied in
Published trials enrolled adults with overweight, obesity or type 2 diabetes, mostly in China. No controlled trial has tested mazdutide in athletes or trained lifters, in pregnancy, or in people with type 1 diabetes.
Unregulated “research” products
Mazdutide cannot be prescribed in the US. The FDA considers online “research use only” mazdutide an unapproved drug (FDA warning letter to Summit Research Peptides, December 10, 2024). No published lab study has tested the content, purity or sterility of such products, so their identity and dose are unverified.
Use in sport
Mazdutide is not named on the WADA Prohibited List, and GLP-1 or glucagon receptor agonists are not listed as a class. The S0 class bans substances with “no current approval by any governmental regulatory health authority” (WADA 2026 Prohibited List). Because mazdutide is approved in China, it does not appear to fall under that catch-all, unlike unapproved investigational peptides. This could change, since the List is revised every year.
Key takeaways
- A GLP-1 and glucagon dual agonist. Mazdutide is a long-acting analog of the gut hormone oxyntomodulin, in the same class as survodutide.
- Approved only in China. NMPA approved it for weight management in June 2025 and type 2 diabetes in September 2025. It is not FDA-approved.
- Weight loss in phase 3. In GLORY-1, 6 mg lowered weight by 14.0% at 48 weeks versus a 0.3% gain on placebo. In GLORY-2, 9 mg lowered weight by 16.7% at 60 weeks versus 1.5% on placebo.
- Beat dulaglutide and semaglutide 1 mg in diabetes trials. DREAMS-2 and the unblinded DREAMS-3 trial reported larger HbA1c and weight reductions, but no published trial has compared it with tirzepatide or with semaglutide at weight-management doses.
- Gastrointestinal effects dominate. Nausea, vomiting and diarrhea rise with dose, reaching about half of people at 9 mg. Heart rate rises modestly.
- Gray-market products are unverified. The FDA treats online “research” mazdutide as an unapproved drug, and its contents have not been independently tested.
Sources
- Shirley M. Mazdutide: first approval. Drugs. 2025;85(12):1621–1627. PubMed.
- Ji L, Jiang H, An P, et al. IBI362 (LY3305677), a weekly-dose GLP-1 and glucagon receptor dual agonist, in Chinese adults with overweight or obesity: a randomised, placebo-controlled, multiple ascending dose phase 1b study. EClinicalMedicine. 2021;39:101088. PubMed.
- Jiang H, Pang S, Zhang Y, et al. 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. Nat Commun. 2022;13(1):3613. PubMed.
- Ji L, Jiang H, Cheng Z, et al. A phase 2 randomised controlled trial of mazdutide in Chinese overweight adults or adults with obesity. Nat Commun. 2023;14(1):8289. PubMed.
- Ji L, Jiang H, Bi Y, et al. Once-weekly mazdutide in Chinese adults with obesity or overweight. N Engl J Med. 2025;392(22):2215–2225. PubMed.
- Gao L, Jiang H, Cai H, et al. Treatment with 9-mg mazdutide for weight reduction in Chinese adults with obesity: the GLORY-2 randomized clinical trial. JAMA. 2026;336(5):377–388. PubMed.
- Ji L, Jiang H, Cheng Z, et al. Mazdutide 9 mg in Chinese adults with a body mass index ≥30 kg/m2 but without diabetes: a phase 2 randomized controlled trial. Med. 2026;7(5):101063. PubMed.
- Bhattachar SN, Tham LS, Li Y, et al. Mazdutide reduces body weight in adults with overweight or obesity: a high-dose phase 1 trial. Diabetes Obes Metab. 2025;27(11):6460–6469. PubMed.
- Hsia SH, Bays HE, Billings LK, et al. Efficacy and safety of mazdutide in adults with obesity or overweight: a US-based, multicentre, phase 2, randomised, placebo-controlled clinical trial. Lancet Diabetes Endocrinol. Published online August 21, 2026. doi:10.1016/S2213-8587(26)00160-9. PubMed.
- Zhu D, Zhao J, Cai H, et al. Mazdutide versus placebo in Chinese adults with type 2 diabetes. Nature. 2026;652(8108):174–180. PubMed.
- Guo L, Zhang B, Xue X, et al. Mazdutide versus dulaglutide in Chinese adults with type 2 diabetes. Nature. 2026;652(8108):181–188. PubMed.
- Luo Y, Jiang H, Shi B, et al. Mazdutide versus semaglutide for the treatment of type 2 diabetes and obesity: rationale, design and baseline data of DREAMS-3 phase 3 trial. Contemp Clin Trials. 2026;160:108150. PubMed.
- Innovent Biologics. Innovent’s mazdutide shows superiority in glycemic control with weight loss over semaglutide in a head-to-head phase 3 clinical trial DREAMS-3. Press release, October 26, 2025. PR Newswire.
- Innovent Biologics. Innovent presents the results of the first phase 3 study of mazdutide for weight management at the ADA’s 84th Scientific Sessions. Press release, June 24, 2024. PR Newswire.
- Kamrul-Hasan ABM, Chatterjee S, Ashraf H, et al. Efficacy and safety of the dual glucagon-like peptide-1 and glucagon receptor agonist mazdutide in predominantly Chinese adults with obesity and/or type 2 diabetes: a systematic review and meta-analysis. Diabetes Obes Metab. 2026;28(10):8777–8794. PubMed.
- National Center for Biotechnology Information. Mazdutide, PubChem CID 167312357. PubChem.
- US Food and Drug Administration. Warning letter to Summit Research Peptides, MARCS-CMS 695607, December 10, 2024. FDA.
- Code of Federal Regulations. 21 CFR 1308.13, Schedule III. eCFR.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA 2026 Prohibited List.