A new study from Rutgers University has found that a common diabetes drug called metformin may reduce the health benefits of exercise.
This is surprising because both metformin and exercise are usually recommended together to help prevent or manage diabetes. But the study suggests that using them together might not work as well as expected.
The research, published in The Journal of Clinical Endocrinology & Metabolism, was led by Professor Steven Malin. His team found that metformin blocks some of the good changes in the body that usually come from exercise—like better blood flow, improved fitness, and lower blood sugar levels.
Doctors have told patients for many years to take metformin and also exercise if they have high blood sugar or are at risk for diabetes. The idea was that two proven treatments should work better when used together.
But Malin said the results don’t add up that way. “Most people think one plus one equals two,” he said, “but our study shows that metformin can actually cancel out some of the benefits of exercise.”
To explore this, the researchers studied 72 adults who were at risk for developing diabetes. These adults were split into four groups. One group did high-intensity exercise and took a fake pill (a placebo).
Another group did high-intensity exercise and took metformin. A third group did low-intensity exercise with a placebo, and the last group did low-intensity exercise while taking metformin.
For 16 weeks, the team tracked how well blood vessels worked when insulin was present. Insulin is a hormone that helps blood sugar move into the body’s cells. Good blood vessel function helps insulin do its job better and lowers blood sugar after meals.
The results were clear: people who exercised but did not take metformin saw big improvements. Their blood vessels responded better to insulin, which means their bodies could move sugar out of the blood more effectively. But for those who took metformin while exercising, these benefits were much smaller.
The researchers also noticed that people who took metformin didn’t see the same gains in fitness or improvements in inflammation and fasting blood sugar. Malin explained, “Exercise helped blood vessel function no matter how hard people worked out, but metformin weakened that benefit.”
This is important because both lower blood sugar and better physical fitness are key goals when treating or preventing diabetes. If metformin makes it harder to improve these things, patients may not get the full protection they need.
Malin pointed out that if someone is exercising and taking metformin but their blood sugar stays high, that’s a serious concern. Also, if they aren’t getting fitter, their daily activities—like climbing stairs or staying active—could become harder over time.
That doesn’t mean people should stop taking their medicine or stop exercising, Malin said. But it does raise questions for doctors. They may need to check more closely how their patients respond to both treatments. More research is needed to find ways to keep the good effects of both exercise and medication.
So why does metformin reduce the benefits of exercise? The answer may lie in how the drug works. Metformin changes how the mitochondria—the power plants of our cells—function.
This can help reduce stress on the body and control blood sugar. But the same changes may stop the body from adjusting well to exercise, especially when it comes to improving fitness and energy.
Earlier studies hinted at this issue, but this study is one of the first to look at how metformin affects blood vessels during insulin use. It shows that metformin might limit the health benefits of exercise in both large and small blood vessels, no matter how hard someone works out.
With about 35 million Americans affected by type 2 diabetes, doctors rely heavily on both lifestyle changes and medication to help people stay healthy. But if these treatments don’t work well together, patients could face more health problems in the future.
“We need better advice for how to combine metformin and exercise,” Malin said. “And we need to look at how other medicines interact with exercise so doctors can help people reduce their disease risk more effectively.”
If you care about diabetes, please read studies about 5 vitamins that may prevent complication in diabetes, and how to manage high blood pressure and diabetes with healthy foods.
For more health information, please see recent studies about vitamin D and type2 diabetes, and to people with type 2 diabetes, some fruits are better than others.
The study is published in The Journal of Clinical Endocrinology & Metabolism.
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