No exercise when you're high

I just learned through my post on ketones that you should not exercise when you’re high. What cut off are you using to determine how high is too high for exercise? She always tests before PE, and I’d like to have a number to tell her.

I use 300.

It is usually recommended that you not exercise with a blood sugar over 250 mg/dl. The concern is that with some individuals and exercise regimes, your blood sugar can actually be raised markedly simply from the exercise. Strenuous exercise can release adrenaline and cortisol and just shoot your blood sugar up. T1 Olympic swimmer Gary Hall reports that his blood sugar rises from 100mg/dl to 300mg/dl after just a 21 second race.

I think suggesting 250 mg/dl as a cutoff point is probably ok, but you might want to be even more conservative. You could always ask Sheri Colberg, she is a member here and with a little bit of work you could also come up with he email.

I think the phenomenon varies with the individual and with the type of exercise (ex. aerobic vs. anaerobic). I use aerobic exercise to help bring my BG down, whether it’s at 250 or 350. The exercise seems to speed up the lowering and prevent the need for further correction boluses. I remember the endo at Diabetes Training Camp, Matt Corcoran, talking about reduced insulin sensitivity with high BGs, and while he wasn’t addressing the issue of exercising with high blood sugar, I’ve found that if I don’t do some aerobic exercise (keeping well hydrated, of course), then it can take a lonnnng time to bring down a high.

Heather, the fact that your BG won’t come down after you’ve been high may relate to ketones. I got this info from my CDE today:

The reason you want to know how the ketones are is because if they are moderate-to-large, Clara would have needed a larger dose than what you would normally give for her correction. When ketones are that high, you now have two problems: 1. not enough insulin, 2. because there isn’t enough insulin (usually an extreme insulin deficiency, such as with a bad site), the body is making ketone bodies because there is nothing to let energy into the cells. At that point, you need more insulin than normal, and just giving the regular correction dose won’t help to clear the ketones. In turn, that means that the blood sugar will also take much, much longer to come down, if at all.

I think different types of exercise affects everyone differently. For me, aerobic or bicylcing drops me quickly. Something like weights I drop very slowly if at all. So I generally try to mix both types of exercise so that I am not dropping too quickly. Basically you need to try different types to see how your daughters body responds. Then you’ll have a better idea. As for when she’s high, I know that if I am in the 300 range it’ll work but anything higher and I don’t have the energy to and I’m too thristy.

Always do a site change first. If that doesn’t fix it and you’re really high, drink as much water as you can, take a gravol to help to surpress the feeling of throwing up and and take potassium tablets (2) and electrolites in the water. I also flood my system with insulin so take a large bolus and put my basal up to 130-150% for about 2 hours. I monitor every 30 minutes and turn the basal back to normal when you hit the 200 range. If this doesn’t work, then I head to the ER.

I’ve always followed the 250 threshold.

Yeah, I feel like the threshold is going to be an individual thing that also depends on how you respond to exercise. I am extremely lucky because running at a moderate pace or walking at a brisk pace will drop my BG quickly. Exercise works for me at BG levels as high as 300 and I’m much less likely to continuing dropping once I stop exercising if I happen to overshoot into a hypo compared to insulin.

Generally, around 250… BUT, you should always consider your symptoms before exercising: Are you terribly thirsty? Are you fatigued? Are you peeing a lot? Those might be good times to reconsider exercising, lest you start spilling ketones… And it’s always a good idea to check for ketones because they can help you make better judgments as to what or what not to do… Yes, I do believe ketone testing is important… and ONE of the reasons why I believe that, is because oftentimes, as Diabetic patients, we get complacent with our day to day care, and if we don’t see something “quote on quote” ‘in writing’, i.e., we have high ketones, we may not take the issue with enough seriousness thinking we can just dose, drink water, and forget it… up on the treadmill… which is a bad idea… Or not understand that we need MORE insulin than usual. Ketones can be a Russian roulette when it comes to how they go, so… with high ketones, always best to go to the ER and then later be sent home, than stay at home and have something bad happen… Just my 2 cents. :slight_smile:

And IAD… on how intense your Physical Activity is

I take a Bolus, wait 15 Min and then proceed

And have to tell you, if this High is a reoccurring problem? Best get to that issue … and finding out why…
anytime being above 140 is not a good thing.

Hello Carb101:

“Too high” depends 100% and entirely on her. Many of us can function quite easily at numbers far, far above the silly “textbook protocols”. But, what that magic cutoff number is that depends solely on her.

Recommendations are over 250-300, but real world can be higher than those. Depends on the how and the why… won’t be at our physical best, but entirely capable of taking part.


I play it by ear between 250 to 350 as far as exercise goes. Will abort if sugar is over 350. Also depends on the activity. A light aerobic session may be just fine between 250 and 350 for me but something more intense that spikes my sugar such as heavy weight lifting or something with sprints or HIT I will cancel. I’m not prone to ketones unless I’m sick but I will abort if ketones are hugely positive.

This would be something you could ask your endo as it might have to be part of the endos orders to the school to implement.

Also keep in mind depending upon age she may have to make up all the missed sessions after school. My daughter (who doesn’t have diabetes) missed two weeks of PE after a bad case of the flu. No choice the kid was really sick but she had to make up quite a few of the missed sessions after school which was a pain in the but. So you don’t want to set it too low or not be able to account for a meal spike if her PE is right after a meal.


I actually exercise as long as I have NO ketones. In my experience, exercise can bring me down faster AS long as I don’t have ketones. So if I test above 300, but test negative for ketones, then I exercise.

If you have a lack of insulin, exercise is dangerous. Otherwise, I think it is OK.

But I guess Clara will not be testing for ketones before PE. So maybe choosing a cutoff, like 300, is best.

I struggled with this while trying to lose weight for my wedding. I wouldnt go by numbers, I’d go by ketone levels. Sometimes my blood sugar would be 260 and I’d have no ketones. I’d exercise even though it was high. Other times it would be 210 with moderate ketones and I’d stay home and drink water. Go by ketones and also how you feel. Take a day off if your sugars are high and you feel crummy! Good Luck.

Thats what i do too! hehe :slight_smile:

I deer hunt. I take 10 days a year off since I was 18 and will never let D beat me. I was dx’d on July 6, 1958 at the age of 3. If I am over 250 I will take some time off before I climb the hill 1.5 miles.

I was told not to exercise above 240. I’ve only been above this twice & I sure didn’t feel like exercising. Risk of further dehydration is something else to consider when high & consider how meters can be off ± by 20 %.

Since kids seem to go high quickly, I’d pick a conservative number.

Make up PE? Really? That would definitely not happen at my daughter’s school.

Most people use the 250 limit but I think its worth explaining why this is recommended.
It is true that aerobic exercise brings your blood sugar down however if you are high it can do the opposite.
This is because if your high, glucose is not getting to your cell or muscle, so the body thinks you are out of energy and starts producing more from the liver (glycogen). The body is unaware that your bloodstream is already full of glucose, and tries to get energy to your muscles but really just makes things worse.
Now, the limit might be 200, 250 or more. There I guess it does depend in part on the person and on the excercise.
Hope I helped :slight_smile: