Editor’s Note: This is the eleventh post in our miniseries about diabetes drugs.
Thus far, this series has been focused on pharmacological methods for treating diabetes. Today, we turn to exercise, which research has shown to be very effective for both preventing and treating this condition.
Several large studies have demonstrated that a program comprised of a healthful diet and physical activity significantly reduces the risk of developing diabetes in people with impaired glucose tolerance. In these studies, dietary modifications have included reduced calorie consumption, a decrease in the consumption of total and saturated fat, a decreased intake of cholesterol, and an increase in the consumption of fiber, whole grains, fruits, and vegetables. The exercise has consisted of an additional 150–240 minutes of moderate-intensity physical activity per week. These lifestyle changes resulted in an average reduction of 5% to 10% of body weight in participants.
Additionally, in each of these studies, the groups that exercised experienced an approximately 50% reduction in their risk of developing diabetes. In the Diabetes Prevention Program Trial (DPPT), a diet and exercise regimen was shown to be better than metformin at preventing diabetes. So it is clear that diet and exercise can significantly reduce the risk of developing diabetes in people with impaired glucose tolerance who are at a high risk for developing diabetes.
But what is the role of exercise in treating people who already have diabetes? This depends on a number of factors, including a person’s type of diabetes, his level of diabetes control, the type of medicines he is taking, what other diseases he has, what other diabetes complications he has, and the type of exercise that he is doing. For people with Type 1 diabetes, exercise can improve cholesterol levels, lower blood pressure, improve insulin sensitivity, and decrease body fat, among other benefits. Exercise also has a wide variety of benefits for people with Type 2 diabetes, including reducing HbA1c (a measure of blood glucose control over the previous 2–3 months) levels between 0.66% and 1.5%, improving the body’s use of insulin, helping control weight, decreasing blood pressure, increasing bone density, and reducing the risk of heart disease.
While there are many benefits to exercise for people with diabetes, it should be noted that there are several potential risks as well, including a worsening of eye complications in people with conditions such as proliferative retinopathy when doing specific exercises (such as weight lifting), hypoglycemia (low blood glucose), and hyperglycemia (high blood glucose). To help ensure a person is healthy enough to begin an exercise program, a thorough evaluation should be conducted by a person’s doctor beforehand.
It is a good idea for people with diabetes to check their blood glucose levels before, during, and after exercise. If blood glucose is less than 100 mg/dl prior to exercise, a small, carbohydrate-containing snack should be eaten. People whose blood glucose level is greater than 300 mg/dl but who do not have ketones (potentially toxic by-products of fat breakdown) present in the blood or urine should use caution when deciding whether to exercise. Those whose blood glucose levels are greater than 250 mg/dl with ketones present should avoid exercise. While every person reacts differently to exercise, with time, people develop a familiarity with their own responses to physical activity and can modify how they monitor their blood glucose accordingly.
Both aerobic exercises, such as walking, running, cycling, or swimming, and resistance exercises, such as weight lifting and using resistance bands, have beneficial effects for people with diabetes. Most health groups recommend a minimum of 30 minutes of moderate-intensity aerobic activity done five times a week, along with two to three resistance exercise workouts each week that include all the major muscle groups.
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