Diabetes

Why Physical Activity Is Important for People with Diabetes

couple walking dog during summer Physical activity is important for everyone, especially those with diabetes. Why? The reason is simple: Exercise can help control blood sugar -- and that's the name of the game with diabetes! When you use your muscles, they need to get energy from somewhere. Most of the time, that energy comes from glucose. Glucose is the sugar running through your bloodstream after you eat. If your muscles use blood sugar for energy, then obviously, the level of sugar in your blood drops. But the effects can last far beyond the time frame of your workout.

For people with type 2 diabetes, regular exercise appears to increase the insulin sensitivity of the body's cells, especially muscle cells. That means cells are better able to uptake glucose from the bloodstream, and they require less insulin to do so. In fact, research suggests that regular exercise can help muscles take up glucose up to 20 times the normal rate. It's not uncommon for people with diabetes to find that they can reduce, and sometimes eliminate, their glucose-lowering medication when they follow a healthy diet and get regular exercise.

Physical Activity Can Prevent or Delay Onset

Several studies indicate that moderate levels of physical activity, in combination with losing weight, can prevent or delay the onset of type 2 diabetes. That's a huge incentive for millions of Americans whose bodies don't use glucose normally. They may be on the brink of developing diabetes and, eventually, the health complications that result.

In fact, a study recently published in the American Journal of Epidemiology bears this out. Boston University researchers used data from the ongoing Black Women's Health Study to study the habits of more than 45,000 African American women between 1995 and 2005. They found that the risk participants faced of being diagnosed with type 2 diabetes was significantly lower among those who reported regularly taking a brisk walk -- even when researchers took into account their age, income, and diet. Getting such regular exercise reduced the risk of diabetes even in participants who were severely obese. What's more, researchers found that participants who said they watched more than five hours of television a day were 86% more likely to develop diabetes compared with those who watched less than an hour day.

Strength training can also be helpful. A 2006 study in Diabetes Care showed that after 16 weeks of strength training, older Hispanic men and women with diabetes significantly improved their insulin sensitivity.

Moderate Intensity Is Best

However, the key is to keep the exercise at a moderate level. Short bursts of intense exercise, such as a sprint, can actually increase your blood sugar levels. So if you have diabetes, it's important to check with healthcare professionals as you develop a plan for regular exercise. They can help you determine when it's important to test your blood sugar.

Anyone with diabetes must contact their doctor before starting an exercise regimen, because in some cases, you'll need to take some precautions. For example, if your eyes suffer from diabetic retinopathy, strenuous activity such as jogging or weight lifting could cause bleeding or allow the retina to detach. And if your feet have nerve damage, a common consequence of diabetes, be sure to visually check for blisters or other foot problems after exercise, and treat them accordingly.

Test Blood Sugar Levels Before, During, and After Exercise

If you take insulin or medications that can cause low blood sugar, test your blood glucose a half-hour before and again immediately before exercising to see if your blood sugar level is stable, rising, or falling.

If your blood sugar is:

Less than 100 milligrams per deciliter (mg/dL), your blood sugar may be too low to exercise safely.
100 to 250 mg/dL, it is generally considered safe to exercise.
250 mg/dL or higher, test your urine for ketones -- substances that accumulate when your body can't use blood glucose for fuel. Don't exercise if you have a high level of ketones.
300 mg/dL or higher, it is too high to consider exercising.

Check your blood glucose after exercise, too; if it's too low, eat some carbs to prevent hypoglycemia.

For details, check MedlinePlus from the National Library of Medicine and National Institutes of Health.

Content from this article originally appeared in Chow Line (8/19/07 and 3/29/09), a service of Ohio State University Extension and the Ohio Agricultural Research and Development Center and was adapted for use on NetWellness with permission, 2009.

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Last Reviewed: Apr 21, 2009

Jackie Buell, PhD, RD/LD, ATC, LAT
Director of Sports Nutrition
College of Education and Human Ecology
The Ohio State University

Carla Miller, PhD
Associate Professor of Human Nutrition
College of Education and Human Ecology
The Ohio State University

Julie Kennel, PhD, RD, CSSD, LD
Director of Human Nutrition Dietetic Internship
College of Education and Human Ecology
The Ohio State University