Prevention of Exercise-Associated Dysglycemia: A Case Study–Based Approach

©2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http:// creativecommons.org/licenses/by-nc-nd/3.0 for details. R egular physical activity is associated with many health benefits for people with type 1 diabetes, including improved quality of life, increased vigor, enhanced insulin sensitivity, and protection against cardiovascular disease and other diabetes related complications (1). Despite its benefits, exercise can aggravate dysglycemia because it causes major changes to glucose production and utilization rates (2). For example, mild to intense aerobic exercise (e.g., walking, cycling, jogging, and most individual and team sports) increases the risk of hypoglycemia during the activity and in recovery because of impaired rates of glucose production, whereas very intense aerobic exercise (>80% of maximal aerobic capacity) and anaerobic exercise (e.g., sprinting and heavy weightlifting) can cause glucose levels to rise because of reduced rates of glucose disposal (3,4). Numerous strategies have been developed to help limit hypoglyce-mia during exercise in individuals with type 1 diabetes. One of the main reasons hypoglycemia occurs is the inability to naturally reduce insulin levels at the onset of exercise (1). Strategies to help limit hypogly-cemia include exercising in the fasted state (5), reducing the insulin for the meal before exercise (6,7), interrupting basal insulin infusion for patients on insulin pump therapy (8–10), and increasing carbohydrate intake (11–14). Continuous glucose monitoring (CGM) can also help to prevent hypoglycemia in people with type 1 diabetes (15). In contrast, very little has been done to develop strategies for exercise associated hyperglycemia, even though the mechanisms for this effect are largely established (16). The inability to naturally raise insulin levels after intense exercise to combat a rise in catecholamines is the main reason why post-exercise hyperglyce-mia occurs (17), although excursions associated with aggressive insulin reductions or excessive carbohydrate intake also likely bear some blame (18). In instances of exercise-associated hyperglycemia caused by intense exercise, insulin concentrations must increase rapidly in the bloodstream to help stabilize glucose levels (3), although evidence is lacking to guide the amount of insulin that should be administered as a correction dose. Unfortunately, glucose control in the hours after exercise is also challenging. There may be increased meal-associated hyperglycemia as a result of insulin dose reductions before exercise or excess carbohydrate consumption to prevent hypogly-cemia (19–21). There also may be late-onset …