Why does my blood sugar skyrocket after exercise? I take a half hour brisk walk every evening a couple hours after I eat dinner. Part of the reason I exercise is to keep things running efficiently. I’d also like to lose a little weight. I have been noticing lately that after exercise, my blood sugar skyrockets well up into the 200s. Tonight I have gone up 85 points after my walk. Why? Now I have to chase it the rest of the evening.
I have been Type 1 for 38 years. Walking has always been a big help. Not any more! I almost think it better to not go.
A few possibilities. Or it could be a combination of several of them.
The first is that your body is releasing glucose to fuel the activity. If you keep doing it regularly though, eventually your body will become more accustomed to it, and this will settle down. It will become easier for your body, and your body will not be as aggressive with the fueling.
The other possibility is your insulin regimen. Are you using the Omnipod 5 loop algorithm? And are you putting it in exercise mode? If so, it might be that the Omnipod is targeting a higher BG number, and that contributes to the BG spike.
Also possible that the Omnipod is seeing a lot of insulin on board (since you do this after dinner), and it cuts off your basal, which contributes to your high BG.
And another possibility is that your dinner is contributing to the spike, since you do this a few hours after dinner.
How about as a test, doing this before dinner one time. And try not using exercise mode on your pump if you have been doing that.
Just do it as a test and see if it makes a difference. If so, it’s easier to figure out how to fix it.
@Cinderfella@Eric is golden with exercise and BG control! He helped me with mine that would start to climb after an hour of swimming and he’s helped numerous others!
I was just thinking of posting about this phenomenon b/c I’ve been struggling with it as well. 40 yrs T1, and the exercise BG thing has always been a challenge. Like you, my preference has been to go within an hour or so after a meal and some insulin on board as a way of knocking my BG down due to the aerobic effect (used to run, but now I bike ride). Works most of the time, but every once in a while it doesn’t. @Eric2 mentions a couple of factors, but here’s one I discovered a few years ago:
OUTSIDE TEMPERATURE extremes. I first noticed this biking in the winter—I like to go when it’s cold out as long as there isn’t snow or ice on the ground (dangerous). I’ve discovered that down to about freezing there are no issues, but below freezing exercise can actually make my bg go UP. Conversely if it’s in the mid- to upper-80s or more, same thing. Goes UP instead of down. Happened to me on my bike ride just yesterday. I’ve recently switched to riding before eating with no IOB (except basal). Temp was around 91° F. Started out at about 120, usual pattern would be to finish a 50-minute ride in the 80s-90s with no IOB. Instead it had gone up to 130 in the first 5 minutes and kept ticking up the whole ride. I even took a couple of units mid-ride, but by the end I think it was around 150. Not as dramatic as what you’re describing, but distinctly NOT the effect I’d normally expect.
Of course there are a LOT of variables that can play into this for T1s (I was also on the last day of an inset/reservoir session and sometimes I get a bit of fade on day 3), but outside temp extremes are definitely a factor for me. My guess is that it’s an adrenal reaction. My body is fine interpreting a bike ride at 40° as Just Exercise, but when it gets down into freezing range some ancient adaptation for escaping from a polar bear or arctic wolf attack kicks in. With high temps it’s probably a saber tooth tiger, but you get the idea. The high one particularly seems to have become more pronounced with age.
My first thought was “if my BG is too high, I need more insulin,” so I was thinking maybe you needed a larger meal bolus. But that’s delicate when exercising, as too much can lead to plummeting BG.
My second thought was that stress raises BG. I know that when I’m working near my limit my BG rises, it doesn’t fall. And Dr. BB noted later that temperature extremes are also stressful, especially in an older body, so that can raise BG too.
Then I read Eric’s post, and he’s exactly right. The thing to do is run some experiments, one step at a time, to find out what is actually going on. Let’s see what happens if the exercise is before the meal so we know whether or not to even think about the food and the meal bolus.
I see worse exercise trends when I am out of shape. Often I see rises like this. If I go skiing for an hour, I might see an increase of 300 points…especially early in the season when I am out of shape.
Some of that is controllable and some isn’t. Could be, in part, dehydration due to the extreme heat.
But, I see patterns like this in the cold, too.
In general, anerobic has a tendency to increase BG, while aerobic tends to decrease, but its variable. My MT pump line used to freeze occasionally, and I suppose its possible that insulin in the tube degrades in some measurable way during intense heat as well.
But, some of this is just flat physiological response, like adrenaline production during exercise.
I don’t have any explanations or scientific backing but here is my experience: I have been a Type 1 for 60 years and play a lot of recreational hockey. I find that that for an hour or two after a game, my blood sugar rises but then begins to drop and can drop significantly if it was an extremely intense game. As well, I see the effects for one or two days after the game and continue to have lower blood sugars.
I go high with any increased activity, including when I have a bunch of appointments in a day. So, it’s not just you. One thing I noticed was that your walks are after dinner. With gastroparesis, the advice was to exercise after meals to speed digestion. So, perhaps your meal is digesting more rapidly, leading to hyperglycemic events that are usually prevented by slower absorption? Is it possible that the composition of your meals makes a difference? Slower digesting foods, such as those with more fat, might change things. Just a thought.
Before retiring, I used to bike to work (Spring - early Fall). I would eat at work after showering, so, with fasting, my blood glucose would soar and I quickly learned to dose insulin before starting out. Same route home in the afternoon and I had to go into exercise mode at least an hour before leaving and have carbs. About 40% of the time I needed to pause for a sugar break. Weird things happen when you exercise and it can be dependent upon the time of the day. Hormone levels change during the day and during exercise which can cause liver and kidneys to dump sugar. Try giving a small pre-exercise dose of insulin (go very slowly and don’t assume that exercise at 8 AM will be the same as 8 PM), slowly increasing if the initial pre-dose is too small.
