Exercise highs and what to do about 'em

So this seems to be a new problem. I’ve always struggled a bit with exercise lows, generally from aerobic exercise (chiefly biking in recent years). But we recently moved to a new place that involves a lot of relatively heavy yard work and household fixery, and particularly in the heat of this season I find it’s having a BG elevating effect. And I don’t know what you do about it, if anything. With exercise lows, I know I’ll have a bounce-back effect within 30min or so of ceasing the exercise, so I don’t treat it with carbs unless it’s really severe, and even then I try to hold back b/c I know it will bounce back naturally to some extent. Is the same true of exertion-induced highs—do they naturally ease back down again? I’m about to eat a sandwich for lunch, after doing some heavy cleaning and junk-moving in a very hot walk-out basement, and my BG is well above what it normally is before lunch. I’m normally around 100, but right now it’s about 140, with nothing else to account for it but the exertion. I’ve actually been watching it ticking up on my Dexcom as I’ve been working. Do you bolus for that? I know everyone’s different, but this is kind of uncharted territory for me, so I’m curious what others’ experiences are.

“Exercise can trigger the body to release stress hormones, like adrenaline and cortisol. Adrenaline can stimulate the liver and the adrenal glands to release glucose and cortisol which makes you more resistant to insulin. Strenuous activity, like competitive sports, can trigger even more stress hormones, in which case blood glucose usually increases (at least temporarily).” This happened to me when I did races 5k. (Internet- Mysugr)

I would wait an 1 hour or 2 to see if it comes down if not then treat it. But 140 is not bad. I would be very cautious as you still have the effect of lowering glucose due to exercise going on as well. Look for a pattern

When I start exercise that i think will break a sweat, I take both insulin and carb, I like carb gels because it is very predictable.
I get a spike at the start of exercise and after a half hour I go low.
I start off with a bolus of 3 units, and then after 20 min i eat my carb gel. Then i eat another if im running low or trending in 30 min or so.

you need to see if your exercise has a predictable pattern.
I figured out my pattern by using a treadmill and watching my Dexcom.

Weird. My BG drops immediately after exercise. Is that normal? I thought it was supposed to rise not drop?

Most people have a rise and then drops out o less you are eating some glucose. Then you have to practice and learn to keep it I. Range

@Eric2 is absolutely the best with exercise tips.


@BoBa_TeA It usually drops with aerobic exercise but has a tendency to increase with anaerobic exercise.


Which has always been my experience until roughly 6-8 yrs ago, when ambient temperature has begun playing an increasing role. I first discovered it while biking. I like to bike into the winter as long as the streets stay free of ice and snow, but one day I came back from a ride in sub-freezing temps, like in the 20sF, and my BG had gone UP to 170 from a starting value ~120. After that I paid more attention and found that this happens when it’s cold enough to (I guess) trigger an adrenal response (“This ain’t exercise—he must be running from a bear!”), and the threshold seems to be drifting higher over time. Now it can happen when it’s in the low 40s outside. And more recently I’ve started noticing it with HIGH temperatures as well, like upper 80s or above. It’s not 100% predictable, so it’s hard to plan around. It’s not a terrible problem—the “spikes” for want of a better term aren’t usually that extreme, it’s just the annoyance of finding I’ve gone up instead of down and not being sure if it will just come down on its own, like how exercise lows usually rebound to normal within an hour or so, or do I need to do something about it if I’m going to bolus for a meal and it’s still affecting me.

We are all so different. I do not rebound from any exercise lows. On my exercise bike if I drop, I just keep dropping until I eat or I’ve stopped in time to not go too low. I use it to stop a climb or I have to short insulin for what I eat so I can get on it. But if I misjudge I have to eat something and that just annoys me to no end. I’ve tried to sit it out, but that has never worked. If I’m “too low” I slowly will just keep dropping.

In my case what was extremely annoying was I would drop the first hour of swimming, so I have to start at about 130, and then I would start to climb and climb. Extreme climbs. I would not eat at all before going because I have issues with eating in the am plus anytime I’ve had insulin for food I really drop at first. But by 3 hours of swimming I have hit 200 plus sometimes. I knew my liver was dumping glucose but how to stop it? It’s not like I could take an insulin dose, I’m out in the middle of the ocean.

In my case Eric pointed out I wasn’t providing fuel to swim for the 2-3 hours that I do and that I need to eat something a few hours before so I had some fuel to burn for my long swim to stop my liver from trying to help. That did help stop the huge spikes when swimming, but lol, I am now combating the problem of spiking when I eat in the am before I swim! So now I am trying to tweak what I do.