"We have found that men and women who incorporate activity into their lifestyles are less likely to develop type 2 diabetes than those who are sedentary. This finding holds no matter what their initial weight," said study author and principal investigator Andrea Kriska, Ph.D., associate professor of epidemiology at GSPH. "This suggests that adopting and maintaining a program of regular physical activity similar to what the Surgeon General's recommendations suggest can play a significant role in preventing type 2 diabetes."
Participating in the study were 1,728 non-diabetic men and women aged 15-59 years who were at least half Pima, Tohono-O'odham or a combination of these two closely related American Indian tribes, both of which have high rates of diabetes.
The amount of participants' physical activity was determined by questionnaire, which assessed leisure and occupational physical activity. Each activity was calculated according to hours per week and relative intensity of the activity. Participants were interviewed and underwent at least one follow-up examination. Unlike other similar studies, this one determined presence of diabetes by an objective measure, an oral glucose tolerance test, rather than by self-reporting by participants.
Over an average follow-up period of six years, 346 participants developed type 2 diabetes. Regardless of initial age or body weight, fewer individuals who were more active (defined as a minimum of 30 minutes of moderate physical activity per day) over this time period developed type 2 diabetes. This finding held in men and women alike, although it was more consistent in women.
The researchers suspect that the apparent differences in effect of activity on development of diabetes in men and women have to do with the study's inadequate assessment of occupational activity, most of which applied to men's jobs.
"Our feeling is that men and women likely reap the same positive results from activity, whether it is in the form of leisure activity or occupational activity," said Dr. Kriska.
This study was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases.