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Why Does My Sugar Go Up After Exercise?


Jun 1, 1994

Question: Why does my blood glucose (BG) sometimes rise after exercise?

Answer: If an inadequate amount of insulin is present in the blood allowing the BG to rise to about 250 to 300 mg/dl, then exercise may cause a further rise in BG rather than the expected drop. Low insulin coupled with physical activity stimulates the secretion of several other hormones such as epinephrine, norepinephrine, cortisol, glucagon, and growth hormone. Collectively these hormones trigger the liver to release glucose into the blood, thereby increasing the BG rather than decreasing it. The hormones also increase the breakdown of fat but limit the uptake of fat by muscle cells. The liver converts some of the fats to strong acids called ketones. The ketones may build up in the blood producing a state called ketoacidosis. This event is far more likely to occur in people with type I diabetes.

To prevent the problem the BG should be checked before exercise and if the level exceeds 250, then exercise should be delayed until it decreases well below 250. The urine should be checked for ketones and if they are present, exercise at this time will exacerbate the problem.

A second cause of the rise in BG during and after physical activity is highly vigorous exercise. The more intense exercise is, the greater the secretion of glucose from the liver. During the strenuous session, stress hormones will be secreted in large quantities which will then stimulate the liver to release glucose. This is an interesting paradox: the more vigorous the exercise the more glucose released by the liver with a likely rise in BG rather than a fall. To make matters worse, the level of stress hormones in the blood may be elevated for several hours after intense exercise causing the liver to continue the outpouring of sugar. Thus, the rise in BG may last for a number of hours once the exercise is completed. Additional BG monitoring may be needed until the values have stabilized.

Athletes who workout strenuously on a regular basis may not need to eat as large a feeding as expected before strenuous sessions. Also, as the body adapts to intense training, the hormonal secretion decreases when the same intensity workouts are done. Consequently, an intense workout at the beginning of a season that caused a surge in BG may cause a lesser rise in BG at mid-season.

In summary, monitor BG before exercise, during exercise if the sessions last beyond an hour, and after exercise one or more times. For non-athletes, high-intensity exercise isn't needed to improve fitness, health in general, and improve BG control. It even tends to make BG management more difficult and increase the risk of injury, sore muscles, and heart attack, and may discourage you from sticking with your exercise regimen.


Categories: Blood Glucose, Blood Sugar, Diabetes, Exercise, Fitness, Insulin



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Comments

Posted by Anonymous on 15 September 2008

I am a type 2 and my bg never gets close to those levels (anymore), but I still have the elevation in BG after exercising. Very angering, makes me want to not exercise.

Posted by Anonymous on 4 June 2009

Measured my BG before a fast 4 mile walk. It was 84. Ate 7 peanut MM's before the walk. 20 minutes after the walk, which took about an hour, my BG was 148. Crazy. No immediate benefits, but dr. said "to keep it up. Exercise is good." We will see.

Posted by Anonymous on 20 May 2012

Yesterday i did some soccer playing and after 25-30 minutes we took a brake. while taking the break i started to feel realy unconfortable and dry mouth when talking with friends. I didn't know what was going on. My GC alwasy been 91 to 105 since i was diagnosed T2 a month ago. After the game i ck my glucose and i was 139 ,i was worry and did'nt know why. I started to do a google search and found the reason. I really appreciate sites like this, a piece of mind for newbies like me. I will keep exercising though, i am loosing weight and feeling much better.

Posted by Anonymous on 29 May 2012

I have had diabetes for many years. Through the years I've upped the intensity of my exercise, started with walking, jazzercise, now I'm doing boxing and sports conditioning. I'm noticing the rise in BG as well. As of right now, I'm going to keep on doing it. For once in my life I am getting fit! I believe the benefits outway the temporary spikes. I'll be seeing my doctor next week, so we'll see!

Posted by Anonymous on 28 August 2012

I just started taking an injection of Victoza to lower my A1c from 7.9 back to my average 6.0. I went to my routine exercise class with a BS of 117. During the exercise I seemed to get fatigued quicker than normal. Had dry mouth and blurred vision. Took by BS when I returned to my car and got a reading of 317. My highest to date was 189. I ate some protien and drank alot of fluids. 3 hours later my BS was down to 85. By then I felt totally wiped out rather than having that bust of energy I usually have after working out. Has anyone else experienced such a dramatic spike while working out on this med?

Posted by Anonymous on 3 October 2012

I have been working out pretty hard since June of this year. I noticed my BG going up during workouts. Been hitting the weights as well. I have dropped Glipizide due to crashing every time I take it, but now I am shooting insulin as well as taking 2K Metformin everyday. Hope I'm going in the right direction because I feel better than I have for several years.

Posted by Anonymous on 26 March 2013

Finally! An explanation that makes sense! Thank you.

I just spent 2-3 hours digging up cottoneaster roots, rested a half hour, then tested: 202 mg/dl. This knowledge will help be predict sugar levels.


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