Although physical activity (PA) is a key element in the prevention and management of type 2 diabetes, many with this chronic disease do not become or remain regularly active. High-quality studies establishing the importance of exercise and fitness in diabetes were lacking until recently, but it is now well established that participation in regular PA improves blood glucose control and can prevent or delay type 2 diabetes, along with positively impacting lipids, blood pressure, cardiovascular events, mortality, and quality of life. Structured interventions combining PA and modest weight loss have been shown to lower risk of type 2 diabetes by up to 58% in high-risk populations. Most benefits of PA on diabetes management are realized through acute and chronic improvements in insulin action, accomplished with both aerobic and resistance training. The benefits of physical training are discussed, along with recommendations for varying activities, PA-associated blood glucose management, diabetes prevention, gestational diabetes mellitus, and safe and effective practices for PA with diabetes-related complications.
Diabetes has become a widespread epidemic, primarily due to increasing prevalence and incidence of type 2 diabetes. According to the Centers for Disease Control and Prevention, in 2007 almost 24 million Americans had diabetes, with one-quarter of those, or six million, undiagnosed (1). Currently, it is estimated that almost 60 million U.S. residents also have prediabetes—a condition in which blood glucose levels are above normal—thus greatly increasing their risk of type 2 diabetes (1). Lifetime risk estimates suggest that one in three Americans born in 2000 or later will develop diabetes, but in high-risk ethnic populations, closer to 50% may develop it (2). Diabetes is a significant cause of premature mortality and morbidity related to cardiovascular disease, blindness, kidney and nerve disease, and amputation (1). Although regular PA may prevent or delay diabetes and its complications (3–10), the majority of people with type 2 diabetes are not active (11).
In this article, the broader term “physical activity” (defined as bodily movement produced by the contraction of skeletal muscle that substantially increases energy expenditure) is used interchangeably with “exercise,” which is defined as a subset of PA done with the intention of developing physical fitness (i.e., cardiovascular, strength, and flexibility training). The intent is to recognize that many types of physical movement may have a positive impact on physical fitness, morbidity, and mortality in individuals with type 2 diabetes.