NEW YORK (Reuters) -- Any type of regular exercise, no matter how strenuous it is, may lower an adult's risk of diabetes, according to a study published in the March 4th issue of The Journal of the American Medical Association.
A multicenter research team, led by Dr. Elizabeth J. Mayer-Davis of the University of South Carolina, reports that both vigorous and nonvigorous exercise are associated with better insulin sensitivity.
"Insulin sensitivity is a very important risk factor for heart disease and for diabetes," Mayer-Davis explained in an interview with Reuters. "People with adult diabetes tend to be what we call extremely insulin-resistant. What this refers to is the ability of your body to use its own insulin to store food so that it can be used for energy. If your body cannot use its own insulin very efficiently, you're at high risk for diabetes. You're also at high risk for heart disease, because insulin resistance usually goes along with obesity, low levels of HDL -- or good cholesterol, and hypertension."
Mayer-Davis and colleagues found that in 1,467 adults, aged 40 to 69 years, the effect of habitual exercise on insulin sensitivity "was remarkably similar for total, vigorous, and nonvigorous activities."
"Both for people who might be at risk for diabetes and for people who already have diabetes, any kind of activity may improve their insulin sensitivity," Mayer-Davis said. "You don't have to go to the gym."
The study population was 38% Caucasian, 28% Hispanic, and 34% African-American. The research team estimated energy expenditure based on interviews with the subjects about a wide range of activities, including hobbies, household chores and sleep -- not just sports and exercise. Glucose tolerance tests were normal in 46% of the subjects, but 22% had impaired glucose tolerance, and 32% had non-insulin-dependent diabetes mellitus.
Regardless of gender, ethnicity, and glucose test results, "...vigorous and nonvigorous levels of (estimated energy expenditure) ...were positively and independently associated with insulin sensitivity," Mayer-Davis and colleagues found. "(I)t is not unreasonable to speculate that regular participation in either vigorous or nonvigorous activity would result in a clinically meaningful improvement in (insulin sensitivity)," they conclude.
The researchers note that the US Centers for Disease Control and Prevention and the American College of Sports Medicine recommend that adults should "participate in at least 30 minutes of moderate-intensity physical activity on most days of the week." These recommendations "are based mainly on evidence from heart disease studies," Mayer-Davis explains. "So our findings add to this with another reason that moderate activity is likely to improve health."
SOURCE: The Journal of the American Medical Association (1998;279:669-674)
