Physical activity and risk for cardiovascular events in diabetic women

Background: Increased physical activity has been associated with reduced risk for cardiovascular disease in the general population, but data are limited on its role among persons with type 2 diabetes mellitus. Objective: To determine whether physical activity decreases risk for cardiovascular disease among diabetic women. Design: Prospective cohort study. Setting: The Nurses' Health Study. Patients: 5125 female nurses with diabetes. Measurements: Physical activity was first assessed in 1980 and was updated in 1982, 1986, 1988, and 1992 through validated questionnaires. Average hours of moderate or vigorous exercise and a metabolic equivalent of task (MET) score were computed. Results: During 14 years of follow-up (31 432 person-years), 323 new cases of cardiovascular disease were documented (225 cases of coronary heart disease and 98 cases of stroke). The age-adjusted relative risks according to average hours of moderate or vigorous activity per week (<1, 1 to 1.9, 2 to 3.9, 4 to 6.9, ≥7) were 1.0, 0.93 (95% Cl, 0.69 to 1.26), 0.82 (Cl, 0.61 to 1.10), 0.54 (Cl, 0.39 to 0.76), and 0.52 (Cl, 0.25 to 1.09) (P < 0.001 for trend). These figures did not change materially after adjustment for smoking, body mass index, and other cardiovascular risk factors (1.0, 1.02, 0.87, 0.61, and 0.55, respectively; P = 0.001 for trend). In separate analyses, levels of physical activity were inversely associated with coronary heart disease and ischemic stroke. Among women who did not exercise vigorously, the multivariate relative risks for cardiovascular disease across quartiles of MET score for walking were 1.0, 0.85, 0.63, and 0.56 (P = 0.03 for trend). Faster usual walking pace was independently associated with lower risk. Conclusion: Among diabetic women, increased physical activity, including regular walking, is associated with substantially reduced risk for cardiovascular events.