Evidence
Advancement to a diagnosis of diabetes can be reduced through physical activity.
The classic physical activity study for diabetes is the Diabetes Prevention Program (DPP) trial (1). Participants with insulin resistance were randomized to a walking intervention vs. metformin. Both showed reduction of advancement to diagnosis of diabetes but the walking group was far superior (58% vs. 31% reduction). The intervention involved walking 2.5 hours weekly. Each group received lifestyle counseling but the walking arm was also provided with places to exercise (e.g., neighborhood walk groups, cardiac rehab units, community based facilities and classes, one-on-one training) and a "toolbox" to help reach goals (i.e. shoes/gym/etc). Individual case managers and coaches made frequent contact with patients. The effect size was seen regardless of ethnicity, age or gender. Other studies have found similar effects in prediabetic patients.
Studies also have shown benefit from exercise in those with diabetes.
An analysis of the Health Professionals Follow-up Study showed that for men with diabetes, physical activity was associated with lower incidences of cardiovascular disease and cardiovascular death and with improvements in overall mortality. Speed of walking and amount of time spent walking were independent variables (2).
This has also been studied from a different angle - reduction of sedentary behaviors can prevent obesity and diabetes.
The authors of this 6-year prospective cohort study estimate that 30% of new cases of obesity and 43% of new cases of diabetes could be prevented by adopting a relatively active lifestyle (<10 h/wk of TV watching and > or = 30 min/d of brisk walking) (3). In the multivariate analyses each 2-h/d increment in TV watching was associated with a 23% increase in obesity and a 14% increase in risk of diabetes.
1. Knowler WC, Barrett-Connor E, Fowler SE, et al. Diabetes prevention program research group, reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393-403.
2. Tanasescu M, Leitzmann MF, Rimm EB, Hu FB. Physical activity in relation to cardiovascular disease and total mortality among men with type 2 diabetes. Circulation 2003;107:2435-2439
3. Hu FB, Li TY, Colditz GA, et al. Television watching and other sedentary behaviors in relation to risk of obesity and type 2 diabetes mellitus in women. JAMA 2003, 289(14):1785-91.