SPH Study: Walking Reduces Diabetes Risk

October 21, 1999

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Frank Hu, assistant professor of nutrition at the School of Public Health, is the lead author of a study that finds that one hour of moderate-intensity exercise (such as walking) per day reduces risk of Type 2 diabetes by nearly 50 percent. Photo by Jon Chase.

New research from the School of Public Health (SPH) finds that moderate exercise, accumulated throughout the day, can lower risk of Type 2 diabetes by nearly 50 percent. While previous research has indicated that physical activity is associated with reduced risk of diabetes, this is the first study to look closely at types of exercise and how they are accrued in relation to risk reduction. The researchers find that both moderate forms of exercise, such as walking, as well as more vigorous forms of activity, are preventive for diabetes. The research is published in the Oct. 20 issue of the Journal of the American Medical Association.

This is encouraging news for the estimated 60 percent of Americans who do not exercise. The researchers focused on walking and found that accumulated moderate physical activity can extend the same benefits as vigorous activity.

"People can cut their risk of Type 2 diabetes nearly in half simply by attaining a total of an hour of moderate-intensity activity each day," said lead author Frank Hu, assistant professor of nutrition at SPH. "The activity can come from a variety of sources throughout the day: walking to the bus stop in the morning, taking the stairs at work, or running errands. It doesn’t have to mean going to the gym and exercising furiously. It doesn’t matter how you get your exercise, just that you get it."

The researchers do not mean to discourage more vigorous forms of exercise, such as aerobics or jogging. The more intense the activity, the faster the protective benefits are realized. There may also be additional health benefits from forms of exercise that leave a person breathless and with a racing pulse. However, for those who can’t – or won’t – engage in a sweaty workout, protection from diabetes can be achieved as easily as walking a bit more each day.

Type 2 diabetes has been characterized as the epidemic of our time. It is a metabolic disorder resulting from the body’s inability to make enough, or properly use, insulin. It strikes in adulthood and is responsible for more than 14 million cases of diabetes in the United States and is the leading cause of new blindness and kidney disease. Diabetes also causes nerve disease, heart disease, and stroke. Each year, at least 190,000 people die from diabetes and its complications.

"People with higher than average risk for Type 2 diabetes are those who are overweight and people who are not physically active," said Hu. Increasing age is also related to risk, with half of all cases found in Americans aged at least 55 years.

With demographic trends in America showing an aging population that is increasingly overweight and sedentary, it is expected that rates of diabetes will continue to rise.

"Physical activity helps to reduce risk of Type 2 diabetes in two different ways," said Hu. "Physical activity often reduces body weight. We know that being overweight is related to a higher risk of diabetes, so losing weight cuts risk.

"Secondly, physical activity improves insulin sensitivity, allowing the body to make better use of its own insulin," said Hu.

The researchers used data from the Nurses’ Health Study, initiated in 1976 at Brigham and Women’s Hospital. "While we performed this research among women," said Hu, "we would expect similar results for men."