Exercise and Diabetes

While it is possible that exercise helps to prevent diabetes, it is certain that regular exercise benefits most people who already have the disorder.

Regular long-term exercise is an important part of diabetes therapy. Exercise promotes weight loss and improves cardiovascular health. It also leads to better control of blood sugar levels, and less risk of diabetes complications. Ultimately, it may even decrease the need for insulin.

Starting an exercise program

It is best to start slowly and gradually build up to at least 25 minutes of aerobic exercise 3 to 5 times a week. Walking, cycling, and swimming are excellent activities. Because exercise has such a profound effect on blood sugar levels and insulin sensitivity, however, you need to take certain precautions.

Before starting an exercise program, get a complete physical exam. Your doctor or an exercise physiologist will help you create a safe program that works best for you.

Here are a few guidelines to help you develop an exercise program:

  • In general, patients with diabetes should not start exercising if blood sugar levels are very high (over 350 mg/dl) or very low (below 60 mg/dl).
  • Keep a record of blood sugar levels, insulin dosages, carbohydrates eaten, and the duration and intensity of the exercise.
  • Choose an appropriate time of day to exercise. If you take insulin, always begin at least one hour after your last injection, but avoid exercise during the time of peak insulin action. It's best to eat something in the two to three hours before and after exercise.
  • Know the symptoms of hypoglycemia, dehydration, and ketoacidosis. It's a good idea to exercise with a partner who also recognizes these signs. Ask your doctor to explain what to look out for and what you should do if symptoms arise.
  • Drink two cups of water two hours before beginning your workout, one to two cups 30 minutes beforehand, and a half cup every 15 minutes during the workout. This helps to prevent dehydration.
  • Patients who take insulin should measure blood glucose before and after exercising. If it is below 100 mg/dl, eat 15 to 30 grams of carbohydrates. Be prepared to stop and measure blood glucose levels during exercise if hypoglycemic symptoms occur. (Always have quick-acting carbohydrate on hand, such as hard candy.)
  • Avoid activities that involve excessive straining, such as weight lifting, if you have diabetic retinopathy. These activities can cause bleeding into the vitreous space in the eye, a serious complication.
  • Finally, stick with it! When your exercise program becomes a consistent part of your life, you'll feel better and have more control over your blood sugar levels.