High blood sugars from exercising, what to do

For the longest time I only associated low blood sugar with exercise, as I would often have to stop my workout to treat a low. However, after doing some research and paying closer attention, I realized that exercise can often cause your blood sugar to rise (a kind of flight or fight response from vigorous workouts that causes the adrenal gland to release adrenaline and noradrenaline into the blood, which then stimulate the liver to release glucose at a faster rate than normal, according to the articles I found).

My question is if your blood sugar does rise from exercise initially, will it over time naturally drop from still having exercised or should you still give insulin to treat that high? I'm sure this answer varies from person to person and each situation, but I was wondering if anyone had insight into spikes in blood sugar from exercising.


My experience is that as long as you have an appropriate level of basal insulin, there is a good chance your blood sugar will normalize after exercise on its own. As to wether a bolus is required, that is complicated. After exercise, your insulin sensitivity can actually double, thus your basal may be more than enough to restore a normal blood sugar. And my experience suggests that bolusing after exercise without eating is a serious hypo risk (at least in my case). I think it has to do with my body trying to restore depleted glycogen and the insulin just causes it all to get sucked up into my muscles at once. So I actually eat after exercise and I only bolus for the meal, not the correction. But everybody is different.

The healthy pancreas will just release more insulin to respond to this spike. However to just inject insulin would be a little too optimistic in my opinion. The muscles are the main reason for the spikes you are experiencing. In an anaerobic state they will release much of their deposits that will be converted in the liver to glucose. But it needs some experience to really rely on this behaviour. With precise knowledge you could start the activity with some carbs and insulin on board. But perhaps it would be easier to start with a vigorous anaerobic exercise. Then after 30 minutes you could switch to an aerobic activity that can consume the spike that has built up. Doing this for another 30 minutes should help to normalize the glucose level again. If this can be handles that way depends very much on your individual muscle / liver reactions.

That makes sense, thank you. I think what has me so confused is that most of the workouts I do are circuits that mix strength and cardio, but some days the same workout will cause me to drop while other days I'll end up high after. I'm going to try ending with a short aerobic activity after to see what happens.

i dont often go high after working out but when i do i go for a walk and that usually brings me down. i correct if im over 200 but it always feels like russian roulette, bolusing for exercise...hate that!

I never realized that I was going high during exercise until I started doing the "Big Blue Test" and then I notice it was happening every time. I have never had to bolus for it because it always returned to near pre-exercise levels in 30 minutes to an hour.

I find the highs from working out, particularly anaerobic things like short, fast runs or lifting (probably circuit training too) seem to be very ephemeral. For running, I set temp basal for 1/2 hour, get ready (10-15 minutes...) run and it'll turn the temp off while I'm still running, if I go fast it usually works out ok, although since I've been running less lately, the individual runs seem to lead to "zippier" insulin response.

For lifting/ pushups/ squats/ etc., I almost always do those in the AM and I have a higher basal beating up DP already and maybe just test, lift and test again. If the first test isn't that high, I'll do a small CB, maybe .3-4U and work out and then see where I'm at and bolus to eat. It really varies every day, I sort of look at the nighttime curve. Sometimes, if I have a couple of really flat BG days in a row, it seems to "turn up" DP so then I'll wake up high and, while it seems like those highs (also liver/ hormone related? hmmm...) are also sort of lighter than the same number from donuts/ cheese fries/ cake, they are still there and I don't like to not fix them.

The intensity of exercise certainly does vary the background level of glucose secreted. The advice I was given which works wonderfully was to have carbs + matching insulin 30 minutes prior to exercise. That way the glucose rise has some active insulin around to counter it, and when I finish exercise my BGL is perfect. Still have to watch out for hypos 2-3 hours later.

Thanks for all the advice, it was helpful!