Walking compared with vigorous physical activity and risk of type 2 diabetes in women - A prospective study

Context Although many studies suggest that physical activity may reduce ris k of type 2 diabetes, the role of moderate-intensity activity such as walki ng is not well understood. Objectives To examine the relationship of total physical activity and incid ence of type 2 diabetes in women and to compare the benefits of walking vs vigorous activity as predictors of subsequent risk of type 2 diabetes. Design and Setting The Nurses' Health Study, a prospective cohort study tha t included detailed data for physical activity from women surveyed in 11 US states in 1986, with updates in 1988 and 1992. Participants A total of 70 102 female nurses aged 40 to 65 years who did no t have diabetes, cardiovascular disease, or cancer at baseline (1986). Main Outcome Measure Risk of type 2 diabetes by quintile of metabolic equiv alent task (MET) score, based on time spent per week on each of 8 common ph ysical activities, including walking. Results During 8 years of follow-up (534 928 person-years), we documented 1 419 incident cases of type 2 diabetes. After adjusting for age, smoking, al cohol use, history of hypertension, history of high cholesterol level, and other covariates, the relative risks (RRs) of developing type 2 diabetes ac ross quintiles of physical activity (least to most) were 1.0, 0.77, 0.75, 0 .62, and 0.54 (P for trend <.001); after adjusting for body mass index (BMI ), RRs were 1.0, 0.84, 0.871 0.77, and 0.74 (P for trend = .002). Among wom en who did not perform vigorous activity, multivariate RRs of type 2 diabet es across quintiles of MET score for walking were 1.0, 0.91, 0.73, 0.69, an d 0.58 (P for trend <.001). After adjusting for BMI, the trend remained sta tistically significant (RRs were 1.0, 0.95, 0.80, 0.81, 0.74; P for trend = .01). Faster usual walking pace was independently associated with decrease d risk. Equivalent energy expenditures from walking and vigorous activity r esulted in comparable magnitudes of risk reduction. Conclusions Our data suggest that greater physical activity level is associ ated with substantial reduction in risk of type 2 diabetes, including physi cal activity of moderate intensity and duration.