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Hello all,

I have a question for the gathered minds. Whenever I do any kind of exercising or extra physical work my BG readings go up about 30-50 points, and stay there for an hour or two afterwards. I used to work out twice a week for over a year and this was always the case. Now that I have a CGM I can watch better. I have started working out this week and I am seeing the same trend. Is this typical? Is there anything special I need to do? Thanks.

Brian H.
 

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It's typical. Exertion like that spurs your cells to call for more energy, which releases glycogen stored in your liver, which raises your blood glucose levels until your cells have used the glucose (depending on the faulty linkage diabetics have to regulate BG/insulin levels). I've seen the same thing when my volunteer gig was moving pallets of frozen food or other high levels of activity.

What to do? If you're using insulin, I suppose you could address the overage. If you're eating according to the standard U.S. diabetic eating plan, you could consider cutting back on carbs. Excess carbs are stored as glycogen; reduce the excess and your body will turn fats and proteins into the glucose it needs (the whole principle behind ketosis). For me (as always, not a doctor) it would depend on how high my baseline BG was and how long my BG was elevated by the exertion.
 

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Agree that a rise is probably typical and looking at cutting carbs should help with not keeping BG up for hours after exercising. My BG has gone up with exercise and it has gone down (exercise in my case is a bike ride that can be 10, 20, 30, + miles). I don't think I have ever nailed down the reason why it does what it does and I can't absolutely predict which way it goes. Well, I do know that after a 100 mile ride it is NOT going to be high.

One thing I think that happens is that the call for refueling from the muscles goes out and the liver delivers glucose to the blood stream if stored glycogen is available. Maybe insulin resistance is lower or higher at times, and when lower, my BG goes down sooner rather than later. When it's higher, the BG goes up and stays higher and longer. That is one thing I think is happening, the other is (remember I mentioned " and the liver delivers....if stored glycogen is available) ample stored glycogen is not always available so not enough glucose is released for muscle energy needs. Thats when burning fats kicks in as the main fuel source, it was also going on to a smaller degree all along and doesn't contribute to BG. For heavy exertions like required for burst of speed or lifting heavy weights, glucose is the fuel of choice. For endurance type stuff like something done over more time and greater distances, we mostly run on stored fat being converted to fatty acids and ketones. The body likes to conserve the glucose for the fight or flight moments.

The conversion of fats to glucose is virtually non-existent and the conversion of protein (amino acids) to glucose is not a fast enough process to meet the latest energy needs so fatty acids/ketones become it. If one has ample supplies of glycogen to convert to glucose for fuel most of the time and then suddenly gets to a point where there is not enough glucose to maintain the same level of exertion, that is when you bonk, hit the wall, run out of gas, etc. If one keeps a low supply of glycogen most of the time then you get more keto adapted and can handle the shift in fuel by merely backing off a little on the exertion and not bonking. Thats why sprinters are not good milers or marathoners.

I would love to have a CGM to monitor my BG on bike rides just to see what's going on, anytime actually. Have you tried doing something more endurance related, like longer continuous walks or bike rides for an hour or more, even on a treadmill or stationary bike? It would be interesting to see if that gave different results than your current exercise. It would also be interesting to see the BG effects of exercising with carb reduction. I would think the amount of rise and duration would also reduce. Realize too that it may take a while to see the effects and won't happen overnight.
 

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I must be completely out of whack. I see my BG actually go down on average of 10 points after exercising. Normally do 30-40 minutes of elliptical machine each morning. I'm type 2 and not on any meds but do a low carb diet.
 

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Discussion Starter · #5 ·
It's typical. Exertion like that spurs your cells to call for more energy, which releases glycogen stored in your liver, which raises your blood glucose levels until your cells have used the glucose (depending on the faulty linkage diabetics have to regulate BG/insulin levels). I've seen the same thing when my volunteer gig was moving pallets of frozen food or other high levels of activity.

What to do? If you're using insulin, I suppose you could address the overage. If you're eating according to the standard U.S. diabetic eating plan, you could consider cutting back on carbs. Excess carbs are stored as glycogen; reduce the excess and your body will turn fats and proteins into the glucose it needs (the whole principle behind ketosis). For me (as always, not a doctor) it would depend on how high my baseline BG was and how long my BG was elevated by the exertion.
I don't use insulin, just Glipizide and Metformin. I try to stay within about 20-30g of carbs for the whole day.
 

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I don't use insulin, just Glipizide and Metformin. I try to stay within about 20-30g of carbs for the whole day.
It does not appear your liver is storing lots of carbs and the glipizide and metformin are doing their job (albeit imperfectly) in manipulating how your body's cells react to the insulin that's released in response to the glucose. I think there's something to what mbuster wrote about the kind of exertion (aerobic/non-aerobic), the duration of the session, and the state of your body at the time (time of day when you're doing the exercise, fuel on board when you do it, previous conditioning, etc.). With the CGM it would be possible to see what's going on with far more clarity than finger sticks.

If my readings were back to my baseline within a couple of hours, then I personally would just let it be as the way my diabetic body works. I'd be concerned about high levels after 3-4 hours but that does not seem to be an issue. And, longer term, if you see this rise increase or if exercise results in hypos, then it would be time to revisit your medication dosages. But otherwise I would consider it a normal (if not entirely welcome) part of diabetes. I hope that helps.
 

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I must be completely out of whack. I see my BG actually go down on average of 10 points after exercising. Normally do 30-40 minutes of elliptical machine each morning. I'm type 2 and not on any meds but do a low carb diet.
Probably not out of whack. You probably have less insulin resistance and the glucose is getting into the cells easier and/or not a big need for a lot of glucose during your activity. Are you trying to hold a good pace on the elliptical or doing high intensity type workouts? Before I got a bike and stopped going for walks as much, a good walk would always end with lower BG when testing after getting back.
 

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I'mt type 2 for the last 15 years and am going to mirror what others have said. The gym for 1 1/4 hours 5-6 times a week plus at least a couple of 20-30 mile bicycle rides a week in the summer. After lifting or cycling my blood is elevated for 2-3 hours. Where my BG benefits is the following morning when my readings are in the 120 range.
 
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