Building Competency in Diabetes Education THE ESSENTIALS

5-46 | CHAPTER 5

compared to late-afternoon exercise. However, it is not reasonable to suggest that physical activity be done only in the mornings. Exercising when insulin is at its peak effect can result in a fall in BG. Medication should be adjusted to prevent hypoglycemia (see Chapter 12: Basal-Bolus Insulin Therapy). 2. Injection sites : Exercise increases the absorption of insulin from the subcutaneous tissue, especially if short-acting insulin is used and the injection site is in an exercising part of the body. The abdomen provides the most consistent absorption of insulin and is generally the recommended site for injections (see Chapter 6: Treatment Modalities: Pharmacological Therapies). 3. SMBG : BG monitoring before, during and after exercise is essential to determine individual response to exercise. Recorded results of SMBG are the most effective tool for determining a pattern of response to exercise, and thus enabling appropriate food and/or insulin adjustments. 4. Food intake : Carbohydrate intake may need to be increased to prevent hypoglycemia. The person’s meal plan should take individual exercise routines into consideration. If the exercise is done regularly, then activity-related food will have been incorporated into the meal plan. In general, people who take insulin tend to overeat before exercise. If a patient is exercising in an attempt to achieve or maintain a healthy body weight, increasing food for exercise will defeat the purpose. Guidelines for increasing food intake to manage BG for activity must be based on BG levels before and after exercise, the duration of exercise, the proximity of unscheduled exercise to usual meals, the time of day and the regularity of exercise. It may be beneficial to delay ingestion of extra food until after exercise, when BG monitoring can help determine the amount of or the necessity for additional carbohydrate. Moderate intensity exercise increases glucose utilization by 2 to 3 mg/kg/minute above usual requirements (201). Thus, a 70 kg person would require approximately 10 to 15 g of additional carbohydrate per hour of moderate intensity activity (i.e. tennis, swimming, cycling). More carbohydrate, approximately 30 to 60 g per hour, is needed for intense exercise (i.e. football, hockey, racquetball, strenuous cycling or swimming) (202). Mild exercise, such as walking 1 km at a leisurely pace, will probably not require any extra food. If a patient’s pre-exercise BG level is under 5.0 mmol/L, then an intake of 10-20 g carbohydrate prior to activity has been recommended (203). The actual amount of carbohydrate will depend on exercise duration and intensity, injected insulin dose and results of BG monitoring. People have varied responses to exercise, so individualized guidelines are crucial.