Karen Schroeder Kassel, MS, RD, MEd
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.
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 move 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, your body does not produce insulin if you have type 1 diabetes. 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.
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 medications, you may be at risk for exercise-induced hypoglycemia.
During exercise, your muscles take up sugar from the bloodstream to convert into energy. This can decrease blood sugar to dangerously low levels. Levels below 70 mg/dL [3.9 mmol/L] may be dangerous depending on your meter and your doctor's guidelines. Hypoglycemia can occur quickly. Symptoms include shakiness, lightheadedness, sweating, headache, hunger, pale skin, irritability, 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:
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 and how much.
Discuss with your doctor when the best time for you to exercise is.
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.
During exercise, check your blood sugar every regularly. 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, since your blood sugar may continue to drop as you recover.
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.
To protect your feet, check for
or other changes after every workout. Buy footwear that is appropriate for the sport and that fit well to your feet. Wear clean, smooth-fitting socks that are made with synthetic fibers.
There are many benefits to exercise, like reduced stress, decreased risk of diabetes-related complications, and better overall health. These benefits far outweigh the inconvenience of the precautions. So, find an activity you enjoy and get moving!
American Diabetes Association
Joslin Diabetes Center
Canadian Diabetes Association
American Diabetes Association workgroup. Defining and reporting hypoglycemia in diabetes. Diabetes Care. May 2005;28:1245-1249.
Blood glucose control and exercise. American Diabetes Association website. Available at: http://www.diabetes.org/food-and-fitness/fitness/get-started-safely/blood-glucose-control-and-exercise.html. Updated December 16, 2013. Accessed January 31, 2014.
Is low blood glucose (hypoglycemia) dangerous? Joslin Diabetes Center website. Available at:
http://www.joslin.org/info/is_low_blood_glucose_hypoglycemia_dangerous.html. Accessed January 30, 2014.
Diabetes and exercise. Joslin Diabetes Center website. Available at:
http://www.joslin.org/info/diabetes-and-exercise.html. Accessed January 30, 2014.
General diabetes facts and information. Joslin Diabetes Center website. Available at:
http://www.joslin.org/info/general_diabetes_facts_and_information.html. Accessed January 30, 2014.
Hypoglycemia. National Diabetes Information Clearinghouse website. Available at:
http://diabetes.niddk.nih.gov/dm/pubs/hypoglycemia/. Updated November 6, 2012. Accessed January 30, 2014.
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_ez/index.aspx. Updated September 9, 2013. Accessed January 30, 2014.
Last reviewed February 2014 by Michael Woods, MD
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