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From Boston, Massachusetts, USA

I am 43, and have had diabetes for 29 years. Every time I've tried to start an exercise program, I get "rewarded" with a lot of low blood sugars, so I give up. Any ideas?


Understanding the possible causes of hypoglycemia (low blood glucose) will assist you in preventing or limiting its occurrence. Hypoglycemia can occur with sudden or unusual intense exercise without adequate additional carbohydrate. Insulin and or oral hypoglycemia agents can also cause hypoglycemia. Too much insulin or oral hypoglycemia medication can bring on hypoglycemia or an error in the measurement of insulin (giving too much), as well as exercise during the peak activity of insulin (when insulin is working its strongest hypoglycemia can occur.

Hypoglycemia due to exercise may occur in people with type I diabetes or people with type 2 diabetes who are treated with insulin or oral hypoglycemic (glucose-lowering medication). People who control type II diabetes with diet and exercise generally do not encounter exercise-related hypoglycemia.

Hypoglycemia can occur during or after exercise as the glucose that was used to fuel the exercise is returned to the muscles and as the action of insulin is enhanced by exercise. Eating can help control this exercise created low blood glucose. However, keep in mind that there are other factors that one can't control that affect the ability of insulin to lower blood glucose.

Tips To help You Avoid Hypoglycemia with Exercise

  1. Exercise 1 to 3 hours after you eat.

  2. Learn your individual glucose response to different types of exercise by monitoring your blood glucose before, during and after exercise.

  3. Check your blood glucose before and after exercise. If you are engaging in an activity for the first time and you are going to spend more than 30 minutes at that activity, check your blood glucose 30 minutes into the activity.

  4. If your pre-exercise blood glucose is less than or equal to 100 mg/dl, eat a snack. If your blood glucose is over 100 mg/dl but not greater than 250 mg/dl, go ahead and exercise. If your blood glucose is over 250 mg/dl, check for ketones. If ketones are present, do not exercise.

    Exercise can worsen your control. If your blood glucose is over 300 mg/dl, whether you have ketones or not, do not exercise. You are not in good control of your diabetes.

  5. Avoid exercise when your insulin is peaking. (Exercise increases blood flow, which increases how fast insulin goes to work.)

  6. Another option is to decrease the insulin dose that will be working while you exercise. Always talk to your health care professional before making any changes in your insulin dose.

  7. You may need extra food for up to 24 hours after depending on how hard and how long you have exercised.

Don't give up! With appropriate adjustments, and with the approval of your physician, people with diabetes can participate in almost any exercise program.


Original posting 15 Dec 1998
Posted to Exercise and Sports and Hypoglycemia


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Last Updated: Tuesday April 06, 2010 15:09:02
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