Each time you exercise, you are placing a stress on your body for which an appropriate response is necessary. This article discusses the body’s response to exercise for the diabetic who is on insulin therapy or insulin secretagogues such as glyburide, glipizide, Glucotrol XL, Amaryl, Prandin or Starlix. It also addresses steps to prevent diabetes-related complications, hypoglycemia in particular, during exercise. Maintaining safe blood glucose levels during and after exercise is accomplished through a correct balance of medications, diet and exercise.

Exercise Yields Consistent BGs

For nondiabetics, blood glucose levels during exercise remain remarkably consistent. This is because the healthy pancreas secretes less insulin in response to exercise, which allows blood glucose to be mobilized from the liver and subsequently taken up by working muscle to be used as fuel.

The current emphasis on tight blood glucose control to prevent complications associated with diabetes increases the potential for hypoglycemia or a fall in blood glucose during exercise. In the case of a diabetic who is treated with insulin therapy or insulin secretagogues, the failure of blood insulin levels to decrease with exercise can result in relatively high levels of insulin and possible hypoglycemia. For this reason, reducing the dose of insulin with exercise may help prevent hypoglycemia. Consult with your diabetes care team for strategies in adjusting insulin dosages to accommodate your exercise needs.

An Insulin-Like Effect

Another potential contributor to exercise-induced hypoglycemia is the fact that exercise has an insulin-like effect. Muscle contractions associated with exercise promote movement of glucose from the blood into the muscle, an action similar to that of the impact of insulin. In fact, exercise alone can result in glucose uptake into muscle, independent of insulin. Thus if too much insulin is present prior to exercise, hypoglycemia may result. On the other hand, too little insulin present and high blood glucose or hyperglycemia may be the result.

The American Diabetes Association has published a position statement on the topic of exercise and diabetes. This helpful resource offers detailed information on the response to exercise for both type 1 and 2 diabetics as well as the impact of complications such as neuropathy and peripheral artery disease on exercise. The statement, “Physical Activity/Exercise and Diabetes,” is available from the American Diabetes Association.

Preventing exercise-associated emergencies:

1. Avoid physical activity if fasting glucose is greater than 250 mg/dl and ketosis is present, and use caution if glucose levels are greater than 300 mg/dl even if no ketosis is present.

2. Ingest additional carbohydrate if glucose levels are less than 100 mg/dl. Consume extra carbohydrate as needed to avoid hypoglycemia. Carbohydrate foods should be readily available during and after physical activity.

3. Inject insulin away from exercising muscles to prevent rapid absorption.

4. Monitor blood glucose before, during and after strenuous exercise, especially when you are just beginning an exercise program. Exercise can result in hypoglycemia as much as four hours after completion.

—Source: ADA