A new analysis from the SURPASS-3 trial has shed light on how the diabetes and weight-loss drug tirzepatide affects muscles in people with type 2 diabetes. P
ublished in The Lancet Diabetes & Endocrinology, the study looked at how this medication impacts muscle volume and the amount of fat stored in muscles—two factors that are important for physical strength and health.
Led by Professor Naveed Sattar from the University of Glasgow, along with researchers from the U.S. and Sweden, the team analyzed data from over 200 people in the SURPASS-3 trial. Their goal was to better understand how tirzepatide affects body composition beyond just reducing overall weight.
Tirzepatide is a new type of medication that helps lower blood sugar levels and promote weight loss. It’s being studied not just for diabetes, but also for its potential to treat obesity. However, there have been concerns that losing weight too quickly or through medication might reduce muscle mass in a harmful way, which could weaken the body and reduce mobility over time.
The study found that while people taking tirzepatide did lose some muscle volume, the reduction matched what would normally be expected from general weight loss. In other words, the loss of muscle was not excessive or unusual.
But more importantly, the researchers found a larger-than-expected decrease in muscle fat infiltration—that is, the fat stored within muscle tissue. Reducing this fat could actually help muscles function better and improve overall strength and movement.
Previous studies using older methods like DEXA scans couldn’t measure these subtle changes in muscle tissue. This new research used more advanced tools to get a closer look, offering better insight into how the body responds to this medication.
Professor Sattar explained that this study is important because many people are worried about whether new weight-loss drugs could harm their muscles. But these results suggest that tirzepatide doesn’t cause unusual muscle loss—and may even make muscles healthier by reducing the fat inside them.
As more powerful weight-loss drugs are developed, researchers say it will be critical to keep checking how they affect muscle mass and strength, especially in people who are older or already have mobility problems. So far, the data on tirzepatide appears encouraging.
In short, this new study offers good news: tirzepatide not only helps people with type 2 diabetes lose harmful body fat, especially around the liver and internal organs, but it may also improve the condition of their muscles by reducing fat within them—potentially leading to better long-term health and mobility.
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The research findings can be found in The Lancet Diabetes & Endocrinology.
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