It’s free. Most people can’t get enough of it. Entreaties to do more of it abound. Yes, it’s the crux of healthy living: exercise. And while just about everyone is better off working out regularly, exercise is, in some sense, the perfect drug for diabetes. Not only can it improve blood glucose control—which in itself reduces the risk of diabetes complications—but research suggests it may combat heart disease, weight gain, depression, and more.

Glucose on the Go
Muscle contractions have a powerful effect on how the body processes glucose, the original biofuel. The muscles are the major consumer of glucose during exercise. It’s not surprising since they do most of the work. In each cell, muscles store dense packets of glucose, accounting for around 2,000 calories worth of energy throughout the body, according to Sheri Colberg-Ochs, PhD, a professor of exercise science at Old Dominion University in Norfolk, Va. “[This energy] just stays there unless you contract the muscle.”

During exercise, the muscles deplete their individual glucose reserves. To help restock their glucose supplies, the muscles change in two important ways: They become more sensitive to insulin—a hormone that escorts glucose from the bloodstream into body cells—and they also start to absorb glucose on their own, independently of insulin.

This second pathway created during exercise is a boon for anyone with type 2 diabetes, which is marked by insulin resistance. “When the body is at rest, it has one mechanism for getting glucose out of the bloodstream. That way is insulin,” says Colberg-Ochs. “What’s so good about exercise is that even if the muscles are insulin resistant at rest, that’s irrelevant with exercise.”

Exercise’s effect on glucose use occurs not just in people with type 2 but in almost everyone, including those with type 1 and pre-diabetes. A large study found that, in people with pre-diabetes, lifestyle changes that included 150 minutes a week of moderate-intensity exercise reduced the risk of progression to full-blown type 2 diabetes by 58 percent.

Exercise makes a little insulin go a long way. That’s generally a good thing. But people who get their insulin from a shot or a pump can end up with too much insulin in the body. That can cause blood glucose to go too low (hypoglycemia), particularly when glucose is diverted to the muscle cells during exercise.

“That’s why some type 1s shy away from exercise,” says Colberg-Ochs. But they needn’t. “If you plan ahead and reduce insulin intake, you can go through exercise without swings in blood glucose.” People with type 2 can also suffer hypoglycemia with exercise because of medication, but the risk isn’t as great.

Exercise’s short-term effects can last anywhere from two hours to three days, according to Colberg-Ochs. “That’s generally why, when we talk about how often people should exercise, we say that they should do it at least every other day, though probably every day is better.” Other benefits of regular physical activity can last a lifetime.

Next: Muscle Up