Exercise and Glucose Control
The prevalence of type 2 diabetes mellitus (T2DM) has increased dramatically in the United States over the past 20 years. The American Diabetes Association recommends regular exercise and maintenance of healthy body weight as important in prevention of T2DM, and exercise is also a cornerstone of treatment regimens for persons already diagnosed with T2DM. T2DM most commonly develops via progressive insulin resistance, a state that has been shown to be caused through several pathways, three of which are discussed in this review. First, the accumulation of lipid intermediates in skeletal muscle under conditions of sustained energy surplus can impair insulin signaling downstream of insulin binding to its receptor. Second, several inflammatory mediators have been shown to negatively affect insulin signaling and gene expression of glucose transporters. Third, oxidative stress induces insulin resistance by creating an environment that interferes with insulin signaling in several ways. Exercise can improve insulin sensitivity by opposing each of these three mechanisms of insulin resistance, as well as providing an avenue for muscle glucose uptake that bypasses insulin, and as such, has the capacity to serve as an important preventative measure. Furthermore, in persons with T2DM, the capacity of muscle contraction to stimulate glucose uptake in a manner that is independent of insulin establishes exercise as a powerful "medicine" in its treatment. Exercise, therefore, serves an important role in prevention and treatment of T2DM.