running and bg levels

D

djm

Member
Messages
7
Type of diabetes
LADA
Hi

I wonder if anyone can point me to some information about how activity affects bg levels. I run twice a week about 5km and find my bg reduces very quickly. I have coped by eating before running and checking my bg before and after. I often have to eat again afterwards. I run about 5 hours after my last insulin injection, and don't want to reduce the amount I am injecting in case I dont get out for my run.

What I dont understand is how my bg is getting used up without insulin - I thought the cells needed insulin to use the sugar.

This is puzzling me, and I am hoping to run longer distances in the future, so I need to understand what is happening.

Any suggestions, information welcome. Thanks
 
phoenix

phoenix

Expert
Messages
5,671
Type of diabetes
Type 1
Treatment type
Pump
What I dont understand is how my bg is getting used up without insulin - I thought the cells needed insulin to use the sugar.
Click to expand...
1) There are pathways that operate during some types of exercise that allow glucose to get into the cell without insulin BUT they are not adequate in themselves, some insulin is always needed.
2) Exercise makes cells far more sensitive so again this reduces the amount of insulin needed
3) However,If blood glucose levels are too high at the start of exercise, the cells will be more resistant to insulin and as the glucose can't enter the cells quickly enough, the body (liver) responds by releasing more gluose into the blood stream. This is why you should test for ketones at above 13-14mmol and not exercise at all if your levels are above about 17mmol.
4) In endurance events, (assuming you are not a low carber), initial fuel is supplied by mainly carbohydrates later on it is supplied by metabolising fat.
(so with distance events your fueling needs will change...for me this happens at about 10 miles but probably wouldn't affect a fast runner in a half marathon)
The runsweet website is good but this article explains things a bit more clearly.
http://www.faqs.org/faqs/diabetes/faq/part1/section-15.html

In practice, getting the balance right means lots of testing before during and after, (and some hours later as hypos are often occur after next mealas liver and muscle fuel reserves are topped up... thats why many people need to reduce insulin for this meal. I also think that as there are so many variables (time of day, what you did and ate yesterday etc) that you have to be prepared for hypos at anytime.... jelly babies or glucose tabs available. Even though I'm on a pump and can reduce basal to a trickle I still have to top up regularly (though I do in general run my blood glucose levels on the low side so i possibly have to be more aware than many).
I test even during events , this would be a problem if you were competitive. Actually, I've found that in races my glucose levels are almost always higher than in training.

Some useful articles on fueling for exercise(by Sheri Colberg)
Effective dietary practices of active people with diabetes: Part 1 (Importance of carbohydrates).
http://www.diabetesincontrol.com/index.php?option=com_content&view=article&id=8045
Preventing hypoglycemia during and after exercise.
http://www.diabetesincontrol.com/index.php?option=com_content&view=article&id=6531
How training affects the fuels your body uses and insulin action.
http://www.diabetesincontrol.com/index.php?option=com_content&view=article&id=6408
Understanding your body’s energy systems and how they impact your exercise blood sugar levels.
(more technical)
http://www.diabetesincontrol.com/index.php?option=com_content&view=article&id=6257
 
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