Diabetes: The Importance of Exercise

Why is exercise important?

Exercise helps keep your blood sugar under control. Many of the people with the best controlled diabetes are those who exercise regularly. Exercise helps in the following ways:

• Exercise helps your body burn more sugar. Insulin is more effective during exercise. More sugar and insulin flows in the blood to the muscles during exercise. As a result, your body burns more sugar. Exercise usually helps lower the blood sugar.
• Exercise makes you feel better. You will have more energy and tire less easily. Studies have shown that exercise can make you feel healthier and happier by helping you keep normal levels of the brain hormones that affect your mood.
• Exercise helps keep the body in good shape. Exercise helps burn extra calories and helps you keep a normal weight. It keeps your muscles and bones strong.
• Exercise helps keep the heart rate and blood pressure lower. People who exercise have healthier hearts. Their hearts don't have to pump as hard. Normal blood pressure helps prevent strokes and heart, eye, and kidney problems.
• Exercise helps keep blood fat levels normal. Many people with diabetes have high levels of blood fats (cholesterol and triglycerides). High blood fats can lead to early aging of blood vessels. Exercise and a healthy diet are the best ways to start trying to reduce blood fats.
• Exercise helps the body become more sensitive to insulin. Research has shown that after 1 hour of afternoon exercise, blood sugars will stay lower until the next morning. Exercise makes the body more sensitive to insulin, the insulin works more efficiently, and usually you will need a lower daily dose of insulin or other diabetes medicines.
• Exercise helps normal blood flow to the feet. Exercise can help maintain good blood flow to your feet and help prevent foot problems.

Exercise is particularly important if you have type 2 diabetes or if you have a high risk of becoming diabetic. If you are overweight, you can lose weight by eating less (particularly less fast food and high-fat food) and exercising more. The risk of developing type 2 diabetes can be reduced by more than half if you maintain a normal weight and exercise regularly.

How do I get started?

Make exercise a daily routine. It is always best to start a new exercise program slowly. Gradually increase how long and how much you exercise.

• Make sure you discuss plans for a new exercise program with your healthcare provider before you begin it.
• If you are taking insulin or other diabetes medicines, discuss how to adjust your dose before and after exercise.

Protect your feet when you exercise. Wear good-fitting shoes and smooth-fitting socks. Check your feet every day and watch for blisters, warm areas or redness. If you develop any sore on your foot, see your healthcare provider right away.

Which kinds of exercise are best?

The best exercise is exercise you enjoy. It is easier to form a habit of exercising if you enjoy the activity. The exercise needs to be aerobic. Only aerobic exercise helps the heart. Some examples are walking, jogging, swimming, and bicycling. Ask your healthcare provider what maximum pulse rate you should work up to.

When activities are done in short bursts with rests in between (such as weight lifting), they are considered strength-building exercises, not aerobic exercise.

People with diabetes participate in almost every sport. Boxing is the only activity that is discouraged. This is because eye injuries are common in boxing, and eye problems are a possible complication of diabetes. Also, the high risk of brain damage makes boxing dangerous for anyone.

Strenuous activities, such as weight lifting and jogging, are discouraged if you have severe eye problems related to diabetes because they increase the pressure in the eyes. If you have eye problems, make sure you talk to your provider before starting a new exercise program.

When should I exercise?

The best time to exercise will vary with your schedule. If you are taking insulin or other diabetes medicines, you need to take precautions against your blood sugar getting too low. Think ahead and make changes in your snacks and doses of insulin or other diabetes medicine to help prevent low blood sugar that might result from exercise. When possible, pick an exercise time, preferably the same time each day, and adjust your snacks and medicine dose to fit the exercise. Adjust your diabetes management to suit your lifestyle. Your lifestyle does not have to be adjusted to fit your diabetes.

How often and long should I exercise?

Ask your healthcare provider to prescribe a plan for starting an exercise program: the type of exercise, how long you should exercise, and how often. The plan should include how you will increase your exercise.

To improve the health of the heart, it is good to have at least 30 minutes of aerobic exercise 5 or more times a week. The more exercise you get, the more fat you will burn. If weight loss is one of your goals, you may need to exercise harder or for a longer time to reach the desired goal.

Start each exercise activity by doing something for 5 to 10 minutes that slowly increases your heart rate. This is called a warm-up. Gently stretch your muscles before and after exercise to help prevent cramps and stiffness. Finish your exercise with a cool-down by gradually slowing your activity for 5 to 10 minutes before stopping.

When should I not exercise?

If you have type 1 diabetes, you may need to watch your urine ketone levels and avoid exercise when you have ketones in your urine. If your urine ketone level is high or moderate, exercise can raise your ketone level even more. Check your urine for ketones before exercising if you are not feeling well or your blood sugar is staying higher than 250 milligrams per deciliter (mg/dL), or 13.9 millimoles per liter (mmol/L).

Also avoid exercising when it is very hot or very cold where you would be exercising.

How can I prevent low blood sugar (hypoglycemic) reactions during exercise?

A low blood sugar (hypoglycemia) could happen during or after exercise. There are several ways to manage your blood sugar and exercise:

• Plan your exercise after a high-protein snack.
• Exercise after a meal, but not until at least 30 minutes after you have eaten (to allow for digestion).
• Reduce your insulin dose before exercise.
• Take extra snacks to help prevent low blood sugar during exercise.

This will take some practice with adjusting the amount of food you eat before exercise, how long you wait before exercising, and how much you decrease your doses of insulin or other diabetes medicine. You will need to keep good records so you can see patterns. Take these records to your visits with your healthcare provider so you can get help making adjustments.

Here are some things that might help.

• Often the best time to exercise is 1 to 3 hours after eating a meal.
• Check your blood sugar before and after exercise. You may need to eat a carb snack (that is at least 15 grams of carbohydrate) before exercise if your blood sugar is less than 100 mg/dL (5.5 mmol/L). Test your blood sugar 15 to 30 minutes later. Your provider may recommend that you not exercise until your blood sugar is higher than 100 mg/dL (5.5 mmol/L).
• Avoid exercising when insulin is working at peak level. (Your provider can tell you when your insulin is at its peak and therefore keeping your blood sugar at its lowest level.)
• Learn how your blood sugar responds to different exercise conditions.
• Know what to do if your blood sugar is low or becomes low when you are exercising.
• Always carry a source of sugar and a longer lasting snack of some carbohydrate and protein, for example, nuts, peanut butter, or cheese and crackers.

Remember, it is wise to THINK AHEAD about the day's schedule and plan accordingly. Be sure to ask your healthcare provider if you have any questions about managing your blood sugar levels, your doses of insulin or other diabetes medicines, and the timing of your exercise.

Abstracted from the book, "Understanding Diabetes," 10th Edition, by H. Peter Chase, MD (available by calling 800- 695-2873).
Published by RelayHealth.
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