High Readings after non-strenuous exercise

I did a search on TU about BG levels rising after exercise. Most were specifically about after high intensity workouts. I get the science behind that, but....

I have been getting slowly into an exercise routine. I walk 20 minutes on a treadmill--about 3/4 mile in 20 minutes, so it is not a strenuous activity.

Until last week, my BG levels would drop 70 points during a 20 minute walk. Last two times(Friday and today) my blood glucose has SOARED. I was 94 when I started this morning and 203 when I finished, 20 minutes later. I had actually delayed my trip to the rec center to get my BG above 70. Same thing last Friday.


The spike after high intensity workouts is just caused by an adrenaline response. So it is fair to conclude that your body feels challenged by your little exercise. The response is the secretion of adrenaline that will trigger the liver to release glucose. I would just continue in the hope that my body will learn that this little exercise is not worth to trigger something like the "run or fight response". If the spike continues to show I would try to extend the exercise to 40min of light exercise. The idea is to consume the spike with the refuling of the muscles that will kick around 20min in the exercise.

One more question, Holger. Why hasn't this happened for the last 3 months? I have been sporadic about it until 2 weeks ago, but the high BGs have only happened today and Friday.

My blood sugar sometimes rises after low/moderate intensity exercise. The same walk that drops me 50 points one day can raise me 30 points another. I've never had an experience of blood sugar spiking 100 points after exercise though.

You mentioned in another post that you had some basal changes after your last endo appointment. If you lowered your basal, the spike might be independent of the exercise. Just a thought...

Take care,


Good thought, Maurie. Thanks!

In my experience the conclusion "more exercise will lead to higher sensitivity for insulin" is correct. However the "price for exercise" is often a more sensitive liver reaction. For example my doc wanted me to exercise 3 times per week to compensate for my desk job. I did that and after 2 months of doing so my liver started to create a much more pronounced dawn phenomenon. As a result I had to cut my exercise level back because on MDI I can not fight the DP. In your case the liver might have learned that it makes sense to proactively release glucose for exercise that is about to unfold. For healthy people this proactive behavior is really helpful. For us in full control of the blood glucose control it is very unpleasant. My hope is that with time your liver will get used to the small increase of stress hormones induced by light exercise.

You could also feed the spike to active insulin. Professional diabetic athletes know their body reaction very well. They often start strenous activity with insulin on board to compensate for the coming release of glucose.

If your exercise is very important for your health you could also ask your doctor about Metformin. This drug works by modulating the liver response down. This will reduce your needs for basal insulin and the spontanous liver reactions will be less pronounced. It all depends on your priorities. Of course the drug will have negative side effects as well - just food for thoughts.

I also experience a strong stress driven response to exercise. Usually when weight lifting or some other anaerobic activity. But I've also seen it when I have become untrained and simply do exercise that I have become unaccustomed to. In that case the response wears off as I do the exercise repeatedly.

Perhaps simply getting your body "practiced" some will reduce the wild blood sugar ride.

I've experienced this increase in DP as well. In my reading it seems to be recognized as a surge in growth hormone overnight. In my case, my DP simply went from bad to badder. And I agree with you on the increase in insulin sensitivity, I've seen numbers that suggest as much as a 50% increase in sensitivity and the effect of exercise can last 48 hours.

Two times is not really enough info to say it's a trend. My guess is stress. Something triggered a stress response, when I was cycling years ago, my BG would spike at the start of a cycling event and if the start was postponed/delayed I would be faced with a very high BG spike.

Keep moving...don't give up...;-)

Have you considered the spike might be caused from going hypo early in the exercise?

It might mean that you are getting in better shape. When I first started running, I turned my basal rate on my pump way down as it seemed my BG would crash. As I ran more and more, I noticed that it wasn't crashing as much but, right around the same time, I got the idea to run farther, which turned into a balancing act, lugging some carbs along, etc. If it runs up regularly and predictably, it probably means you're not getting the bang for your buck and to leave your basal higher if you're adjusting it or eating to work out. 20 minutes seems to work out to about 8G of carbs for me but everyone's different and it's just a matter of checking, testing and making decisions about how best to keep the balance. Maybe go 30 minutes, maybe a small bolus if you walk for 10 minutes, test and it's going up, knock it down.

This may be more related to you low rather than your exercise. If your body perceived the low as a hard low and released a liver dump to compensate, then you can go high and stay there for quite a while. The exercise would just be reinforcing the liver dump from the low.

Have you addressed the cause of the below 70s yet? You may need a lower basal in the time leading up to the sub 70s.

Or did you over correct for the low and had a bit of an over shoot?

I find that my blood sugar can surge immediately following exercise, especially if it involves lifting weights or other strength-building exercise. BUT I notice a trend for several days afterwards of lower sugars leading me to believe that overall the exercise has a nice effect on me long-term but requires more insulin short-term. IT does seem counter-intuitive to be giving insulin while exercising. So T1s have not only their pancreas to contend with but also the liver! Blast!

All great advice. I kind of followed Maury's thought today. I was 174 pre-exercise (that is truly stress--my husband has had flu kind of symptoms for over a month and I dragged him to my doctor this morning as he sees a nurse at his...)

I walked for 23 minutes, but upped the pace. I walked 1.25 miles, including the slow down. I was 120 directly after and 131 an hour later.

I am glad to be exercising some again--and all you help is very encouraging.

203 while higher number than comfortable is hardly "soaring".

Regardless, entirely possible what you never caught was an even lower reading before the 94, and the 203 is a bounce?

With exercise of any type the general rule is to give yourself a buffer through which your exercise(s) must eat through.

Rather than 100 and exercising do it from 150, 200... take a snack before you exercise so you cannot crash, regardless of intensity or its lack.

Dont forget the adrenaline system either...

Be REAL careful to play with insulin to drop sugars resulting from exercise(s). Insulin absorption will play a role, and its very dangerous to be too aggressive if well meaning.

Be careful!!!!

My BG increases by 60-70 after a fairly intense one hour weights session. I normally start with a BG around 80-100. Although I may be 140-170 afterwards this generally drops back to normal fairly quickly. If anything I can drop too low about 4 hours after weights exercise and need to keep an eye on this. I kinda like that I know my BG will steadily rise during weights workouts as it means I don’t have to worry too much about lows (I still carry glucose with me though!).

I think 80 to 100 is too low to start exercising, I tend to try and get mine above 150 and also eat some slow acting carbs. I think what you are seeing is the rebound from a low. When I rowed crew (way before BG meters). I always ate a candy bar before a race otherwise I would go very low right after.


It’s definitely not a rebound from a low, which is confirmed by CGM. My experience is that exercise has markedly different effects on BG depending on intensity and time of day among other things.

Hi Spock,

I have noticed a few times that my bg has increased when exercising, but this isn't usual for me. Usually a walk of 1-2 miles will always lower me as will shopping etc. Last week I went for a bike ride of about 1 mile to see if it would lower me but I went up. I'm wondering if it was the different muscle groups used as some people seem to go up from weight lifting etc. But bicycle riding is more like walking/aerobic exercise for me so I think it must have been something else.