Featured Expert Blog

Avoiding Hypoglycemia While Exercising

Sometimes people with diabetes don’t want to exercise because they are afraid of having their blood sugar go too low. Most often this happens to people with type 1 diabetes, but it can be a significant concern for those with type 2 diabetes who take mealtime insulin.

Understanding how the body reacts to exercise can help you choose the right strategies to prevent or reduce the episodes of hypoglycemia and continue to enjoy the benefits of exercise, which we know are innumerable for those with type 2 diabetes.

When exercise begins, the body provides fuel from glucose that is stored in the muscle cells. Muscle cells have a limited amount of glucose so after about five to ten minutes of exercise, the liver becomes the main source for glucose output, initially by the breakdown of glycogen (glucose molecules put together). Eventually the liver will begin to make new glucose molecules in a process called glucoenogenous. During exercise, insulin release by the pancreas is depressed to encourage the release of glucose from storage depots.

The metabolic profile in low- to moderate-intensity exercise, such as walking or casual biking, is one of reduction in blood glucose levels: uptake of glucose by the working muscle exceeds glucose release by the liver. As the duration and or intensity builds up to moderate levels or beyond, the risk of hypoglycemia (dangerously low blood sugar) becomes more prominent.

Because resources to build glucose from protein backbones are limited, the body uses another energy source to fuel prolonged exercise. After about 20 minutes, free fatty acids from the stored fat pool are burned along with glucose for fuel. That’s why low-intensity exercise of moderate duration is an excellent weight loss strategy and has engendered the aphorism, “slow and steady wins the race.”

But the metabolic profile shifts significantly when you engage in vigorous activities, especially resistance type exercise. Instead of being a minor player in the hormonal milieu, adrenaline release ramps up, causing a glut of glucose release by the liver. This momentarily upends the balance between glucose entering the bloodstream and glucose being absorbed by the muscle cells towards higher glucose levels in the blood. That is why glucose levels can appear to paradoxically rise after exercise. This elevation is temporary and uptake of glucose by the muscle cells will continue for 24 to 48 hours post exercise.

Making sure your blood glucose is in the safe range before exercise (between 110 and 180mg/dl) and after exercise is vital to reducing the risk of hypoglycemia.

As a general guideline you will need approximately 15 to 30 grams of carbohydrate for each hour of moderate-intensity exercise you do. If you are going to exercise for longer than one hour at a time, it is important that you check your glucose levels every hour during exercise and adjust your carbohydrate intake accordingly.

You can take advantage of the different effects on glucose levels of moderate aerobic and resistance training to avoid hypoglycemic episodes by combining them on the same day by starting with a resistance workout and finishing with aerobics. The high glucose levels produced by the resistance training will be absorbed by aerobic activity with less of a possibility of hypoglycemia.

Live well and enjoy!

4 Comments Post a Comment
by BigWatusi, Jun 16, 2013
Good information.  I am a type 1 and a nurse but this part of being diabetic has always stumped me and exercise related hypoglycemia has been hard for me to control.  Thanks for writing such a relevant article.

by Nora Saul, M.S, R.D., L.D.N., C.D.EBlank, Jun 16, 2013
Dear BigWatusi,
Thanks very much for your comment.

by oozyonson, Jun 17, 2013
That's the best information I've ever heard and explains some of the paradox I find when I weed my garden or go shopping after a moderate amount of food. I never knew why it happened or the process. Thank you for sharing this!

by Santi314, Jun 17, 2013
Extend Bar (which is carried at Walgreens) is clinically proven to help avoid hypoglycemia during exercise. I use them for long-distance cycling.

Post a Comment
Diabetes Rewards Promo
Popular Resources
image description
Refill Prescriptions
Refill a prescription from your history. We'll have it ready or shipped FREE.
image description
Walgreens Mobile App
Refill your prescriptions‚ anytime, anywhere‚ with our app.
image description
Prescription Refill Reminders
Set up to receive timely refill reminders via text or email.
image description
Immunization Services
Get the whole family immunized with CDC-recommended vaccines.
image description
Health Test Services
Identify your risk for heart disease, diabetes and more with a health test.
image description
Caregiver Services
Get prescription and home care resource support for your loved ones.
Weight Tracker
Track your weight over time
Start Tracking Now
Recent Discussions
checking sugar in AM 4 hours by 7431 after fasting & sleeping not sure if I ck blood sugar immed...
Has Victoza helped anyone with weight loss? May 18, 2010 by bke64 I have Type 2 Diabetes and was put on Victoza yesterday, my ...
ANYONE LOSS HAIR WHILE ON VICTOZA Apr 22, 2013 by xstitchnheaven I have type 2 diabetes. My doctor prescribed Byetta and I tr...
Diabetes Tracker
Track glucose levels and carbs
Start Tracking Now
Ask an Expert
Exercise Tracker
Track exercise activity
Start Tracking Now

The contents of this website ("Site") such as text, graphics, images, and other material contained on the Site ("Content") are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the Site. If you think you may have a medical emergency, call your doctor or 911 immediately. Walgreens does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned on the Site. Reliance on any information provided by the Site or other users to the Site is solely at your own risk.

The opinions expressed on this Site in user-generated Content areas including but not limited to: Expert Blog; Communities; and Ask an Expert Forum are solely those of the relevant user, who may or may not have medical or scientific training. Walgreens does not review user-generated Content for accuracy, and user-generated Content does not represent the opinion of Walgreens. User-generated Content may contain information about treatments or uses of drugs or products that have not been approved by the U.S. Food and Drug Administration.