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If you have diabetes, exercise can help keep blood sugar under control and promote good health. But, there are precautions you should know about. While exercise is beneficial because it can lower your blood sugar level, it can also be dangerous for the same reason. Exercise can lead to hypoglycemia —a quick drop in blood sugar.

The Importance of Balance

Living with type 1 diabetes requires a balance of eating, exercising, and insulin usage to keep blood sugar levels within a desirable range. People without diabetes rarely give blood sugar a thought. This is because the pancreas automatically produces insulin to escort sugar out of the bloodstream and into body cells for use. Insulin production is naturally matched with the amount of sugar in the blood to keep levels stable.

But, with type 1 diabetes your body does not produce insulin. So you must take over as the regulator of blood sugar. This is an important job, as both high and low blood sugar levels can have serious health consequences.

In type 2 diabetes , your body produces insulin, but your body either cannot use it properly or does not make enough. People who manage type 2 diabetes with meal planning and exercise usually do not have problems with hypoglycemia. But if you use insulin injections or take some types of oral medicines, you may be at risk for exercise-induced hypoglycemia.

What Is Hypoglycemia?

During exercise, your muscles take up sugar from the bloodstream to convert into energy. This can decrease blood sugar to dangerously low levels (eg, below 70 mg/dL [3.9 mmol/L] depending on the meter and your doctor's guidelines). Hypoglycemia can occur quickly. Symptoms include shakiness, dizziness, sweating, headache, hunger, pale skin, sudden moodiness, clumsy movements, confusion, and tingling around the mouth. Severe hypoglycemia can result in unconsciousness or seizures.

But do not let the risk of hypoglycemia keep you from the many benefits of exercise. With a few precautions, you can re-establish the balance of food, exercise, and insulin. Here are some guidelines for safely incorporating exercise into your lifestyle:

Talk to Your Healthcare Team

Your healthcare team can personalize your exercise goals. Depending on factors like how long you have had diabetes, your age, and other health problems, your doctor may do an exam and testing to find out the type of exercise that is safe for you.

Time It Right

Discuss with your doctor when the best time for you to exercise is.

Monitor Your Blood Sugar Closely

Check your blood sugar before, during, and after exercise, and record these numbers. You and your healthcare team can use these readings to determine any changes in your insulin dose. With regular exercise, your need for insulin may decrease.

Before exercise, check your blood sugar twice: 30 minutes before and a few minutes before. This way, you will see if your blood sugar is decreasing. If it is dropping or it is 100 mg/dL (5.6 mmol/L) or less, have a small snack and wait for your blood sugar to return to normal. People with type 2 diabetes may be advised to avoid extra snacking because it may interfere with weight loss (ask your doctor). If your blood sugar is high—250 mg/dL (13.9 mmol/L) or more—do not exercise. Instead, check your urine for ketones. Do not exercise until both blood sugar and ketone levels return to normal.

During exercise, check your blood sugar every 30 minutes. If blood sugar levels drop too much (ask your doctor what level is too low), stop exercising and have a snack. Also, be aware of high levels. Ask your doctor when to check for ketones and how best to manage high blood sugar.

After exercise, check again. If your exercise session is long, check regularly for several hours after, as blood sugar may continue to drop.

Be Prepared

Always have blood testing equipment, insulin, and high carbohydrate snacks with you. Good snacks include juice, soft drinks, glucose tablets or gel, or hard candy. If hypoglycemia is a recurring problem, ask your doctor about a glucagon injection kit to treat a severe case. Carry a water bottle and drink often.

Manage Complications

To protect your feet, check for blisters or other changes after every workout. Buy footwear appropriate for the sport and that fit well to your feet. Wear clean, smooth-fitting socks (made with synthetic fibers).

Get Moving!

There are many benefits to exercise, like reduced stress, decreased risk of diabetes-related complications, and overall better health. These benefits far outweigh the inconvenience of the precautions. So, find an activity you enjoy and get moving!

RESOURCES

American Diabetes Association http://www.diabetes.org/

Joslin Diabetes Center http://www.joslin.org/index.html/

CANADIAN RESOURCES

Canadian Diabetes Association http://www.diabetes.ca/

Health Canada http://www.hc-sc.gc.ca/index%5Fe.html/

References

American Diabetes Association workgroup. Defining and reporting hypoglycemia in diabetes. Diabetes Care May 2005;28:1245-1249.

Are low blood sugars dangerous? Joslin Diabetes Center website. Available at: http://www.joslin.org/info/is%5Flow%5Fblood%5Fglucose%5Fhypoglycemia%5Fdangerous.html . Accessed May 17, 2012.

Diabetes and exercise. Joslin Diabetes Center website. Available at: http://www.joslin.org/info/diabetes-and-exercise.html . Accessed May 17, 2012.

Diabetes and exercise: when to monitor your blood sugar. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/diabetes-and-exercise/DA00105 . Updated February 24, 2011. Accessed May 17, 2012.

General diabetes facts and information. Joslin Diabetes Center website. Available at: http://www.joslin.org/info/general%5Fdiabetes%5Ffacts%5Fand%5Finformation.html . Accessed May 17, 2012.

Hypoglycemia. National Diabetes Information Clearinghouse website. Available at: http://diabetes.niddk.nih.gov/dm/pubs/hypoglycemia/ . Published October 2008. Accessed May 17, 2012.

Puzanov I. Hypoglycemia. EBSCO Patient Education Reference Center website. Available at: http://www.ebscohost.com/pointOfCare/perc-about . Updated September 1, 2011. Accessed May 17, 2012.

What I need to know about physical activity and diabetes. National Diabetes Information Clearinghouse website. Available at: http://diabetes.niddk.nih.gov/dm/pubs/physical%5Fez/index.aspx. Updated December 6, 2011. Accessed May 30, 2012.

Revision Information

Reviewer: Brian Randall, MD
Review Date: 05/2012 -
Update Date: 05/17/2012 -

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.