The impact of exercise on insulin action in type 2 diabetes mellitus: Relationship to prevention and control

Abstract

Background: The interactions between insulin and physical activity are varied and complex. Control of blood glucose levels relies heavily on the balance between insulin and opposing counterregulatory endocrine hormones that bind to their respective receptors in muscle, adipose, and liver tissues. Other metabolic factors-such as fuel use and availability, exercise intensity and duration, training status, and visceral fat levels-also affect physical activity done by individuals with insulin resistance and type 2 diabetes mellitus (DM). Objectives: The purpose of this article was to discuss how certain variables interact with acute sessions of physical activity and more extended exercise training, focusing special attention on their relationship to both exercise and resting glycemia as it relates to type 2 DM prevention and control. Also discussed are strategies that individuals with type 2 DM can use to engage in appropriate physical training to control DM and prevent other insulin-related health problems. Methods: The content of this article was based on an electronic search of the literature using PubMed and the selection of key search terms alone and in combination, including exercise, aerobic training, resistance exercise, insulin, hyperglycemia, diabetes, diabetes prevention, and humans. Articles that appeared in relevant, combined searches of these terms were examined back to the year 2000. A secondary search of articles related to type 2 DM and exercise was conducted via references found in these cited studies that met the search criteria. Results: Current research suggests that type 2 DM can be prevented and controlled with increased physical activity. With respect to the possibility of reversal of a prediabetes state, both aerobic and resistance training may play important roles in these processes. Although individuals with DM are usually instructed to exercise to improve control of their disease, their special metabolic situation can lead them into hypoglycemic or hyperglycemic conditions. When recommended guidelines are followed, however, physical activities can be done safely and effectively. In addition, abnormal insulin action in the body is associated with not only prediabetes and DM but also with a host of other insulin-related health conditions, including cardiovascular disease. Conclusion: A more thorough understanding of the association among insulin, exercise, glycemia, and DM will lead to better control of these independent factors in health and disease states. © 2006 Excerpta Medica, Inc.