Mazdutide: One Peptide Key for the GLP-1 and Glucagon Locks

After you eat, your gut sends out a small hormone with a neat trick. It fits two different locks on your cells at once. One lock helps calm hunger. The other can help the body burn more energy.

Mazdutide is a lab-made version of that hormone, built to last much longer. In 2025, China became the first country to approve it. Here is how it works and what studies have found.

What it is

A peptide is a short chain of amino acids. Think of amino acids as beads and a peptide as a short bead bracelet. New to this? Start with what a peptide is.

The natural hormone is called oxyntomodulin. Let's call it OXM. It is a bracelet of 37 beads. Your gut lets it out after a meal, along with its famous cousin, GLP-1.

Scientists found OXM in the early 1980s. Its odd name comes from the stomach. It acts on the glands there that make acid.

OXM has one weak spot. It does not last long in the blood.

So mazdutide was given a fatty tail. The tail helps it stay in the body much longer. That is why it was built as a once-a-week medicine.

Two drug makers work on it together. One is Eli Lilly in the US. The other is Innovent, based in Suzhou, China.

What it does in the body

Mazdutide works through receptors on cells. A receptor is a lock, and the hormone is the key.

Mazdutide fits two locks. The first is the GLP-1 lock. It helps turn down hunger. It also helps the pancreas let out insulin when blood sugar is high.

The second is the glucagon lock. Glucagon is a hormone that pushes blood sugar up. That sounds like an odd pick! But glucagon can also make the body burn more energy.

Here is the clever part. The GLP-1 side pulls blood sugar back down. So the two locks balance each other.

What scientists have found

In cells: In lab tests, mazdutide latched on tightly to both locks. It grabbed the human and the mouse versions of each one.

In animals: In early mouse work, it improved blood sugar control and lowered body weight. The mice also burned more energy. It even cut weight in mice missing one of the two locks.

In a 2025 study, mice ate a high-fat diet for 13 weeks. Then they got mazdutide or semaglutide, a GLP-1-only medicine, for four weeks. Scans showed liver fat fell more with mazdutide.

In people: The big trials brought striking results. GLORY-1 was published in 2025. It followed 610 adults in China with obesity, or extra weight plus a related health problem.

After 48 weeks, weight fell 11% to 14% on average, depending on the dose. On placebo, a dummy look-alike, it barely changed.

Then came GLORY-2, with a higher dose. It followed 461 adults in China with obesity for 60 weeks. Weight fell about 17% on mazdutide and 1.5% on placebo.

Lilly has tested it in the US, too. A trial of 179 US adults with obesity or extra weight was published in 2026. On the highest dose, weight fell about 18% in 32 weeks. On placebo, it fell about 1%.

The most common side effects were in the gut, like nausea, vomiting and diarrhea. Most were mild to moderate. On the highest US dose, more people stopped early because of them.

Where it stands

Mazdutide has been approved in China since June 2025, but it is not approved by the FDA.

China first approved it for long-term weight management in adults. In September 2025, it was approved there for blood sugar control in type 2 diabetes, too.

Trials are now exploring fatty liver disease and sleep apnea. Scientists also want to learn how much the glucagon lock adds in people over the long run.

Its cousin tirzepatide fits a different pair of locks, GLP-1 and GIP. With trials growing worldwide, mazdutide is one to watch.

The bottom line

• Mazdutide is a long-lasting, lab-made version of OXM, a gut hormone that fits both the GLP-1 and glucagon locks.
• In mice, it cut liver fat more than semaglutide. In large trials in China, weight fell 11% to 17% on average.
• It has been approved in China since 2025. New trials in fatty liver disease and sleep apnea are the exciting next step.