"Magic" exercise & blood sugar equation? my BG goes way up with exercise

My doctor told me today that there is a somewhat complicated equation about exercise and BG levels. She will go through it with me when I see her next month. I’ve been diabetic for 23 years and have never really had an issue with BG going up with exercise. But in the last 6 months I have been doing Muay Thai kickboxing and it’s insanely strenuous. If I am above 200 ( not higher than 230) when I start it goes up for the entire day. If I correct my normal amount, I crash badly. So I correct half. If it’s in the 120-150 range I crash during it and can go through 3 juice boxes in an hour.

Anyone know of this equation idea my doctor is talking about? I’d rather not wait another month to find out. Thanks!

is a chart I found useful, the way it works is like for “high intensity” exercise for an hour, you only bolus 50% of your preworkout snack and burn off the rest? If you are high and do a CB, you do 50% if you are in the middle of an hour session. One thing about my experience with martial arts, Tae Kwon Do at an old school place, not competitive, more about kicking your own butt than other people’s but we did some sparring too, is that the sparring sessions tended to be at the end of class, and sort of give me a huge adrenaline rush on top of the “correction” snacks during class so then afterwords I’d run high. It’s hard to guess without knowing more about what exactly you are doing (both in terms of BG and in terms of your workout…) but it would be my guess that you might be running into that? I think more smaller snacks can be a useful alternative but it can get in the way of the flow of things too. Good luck!

Sure. We did burpees and quite a bit of other sort of hyperkinetic activity whilebeing urged on for an hour. I liked it a lot. I was also very sedentary when I started but am sort of hyper now. I try to get insulin on board out before I start and then have a small snack. These days I’m mostly running but if you are hitting stuff and/ or being aggressive, I’d suspect there’s some adrenaline that would benefit from some insulin, although very small doses? All of it is trial and error. The other thing I’ve experienced, exercising since about 2006 or so, is that I think I change over time and the benefits seem to slowly diminish? My heart rate, BP, etc. all still get benefits so it’s worth it but it doesn’t kill my BG as much. Maybe try some cardio only “flow” stuff on your day off or something like that?

I would actually probably delay or skip exercise if my BG was 220. If you exercise with a high blood sugar and you get really high like 300, you can start to initiate the same sort of thing that happens with DKA. You liver can get huge signals to dump blood sugar and it can cause problems. I like to start my exercise like acidrock, with some food in my belly on the way to fuel my workout and some insulin on board. Sheri Colberg in “The Diabetic Athlete’s Handbook” has very good advice.

I weightlift and my blood sugar always goes up, so I actually eat and bolus (a little extra) before working out. Then, after workout I need to be careful, I will be insulin sensitive. If my blood sugar is high right after workout, I can correct, but probably need to double or triple my insulin sensitivity factor. I basically never correct after workout. Instead, I eat and bolus for the meal. I actually halve my meal bolus (again, you are insulin sensitive).

It may be too that if your insulin is turned up too high, the workouts are mixing it up w/ “spare basal” and forcing you to eat which, in turn, pushes your BG up? It might be worth it to explore turning a rate down a notch or two. While it may seem counterintuitive to turn your insulin down if you are running high, it can work out well to do that? If your BG is smoother and more stable, I susepct you’d find yourself feeling a bit more energetic. It may also be advantageous to add in some cardio kinds of things that might have more flow and less adrenaline/ stress/ excitement than sparring types of activities?

I’m afraid I have to disagree with your doctor! There may exist some complicated equation but like everything to do with diabetes, it’s theoretical and what’s ‘in the book’ will vary in its application from individual to individual.

In my T1 carb-counting class we did a session on insulin and exercise, and boy was it eye-opening. So the theory ‘in the book’ was : exercise usually lowers BG but can sometimes raise BG.

So we all took our BGs then had the choice of 2 exercise sessions. All but 2 us opted for a half hour brisk walk. The remaining two, both young, fit gym female bunnies, went for a half hour run.

We then came back and took our BGs again. Most of the walking group had small changes in BG, some up and some down. One of the gym bunnies was just above 200 before her run. When she returned from the run, she was above 300.

So I’d say don’t hold out hope for an equation, but use any theory as a guide to work out your own mileage.

For me, any activity that involves a lot of adreneline causes my BG to go up. Sometimes way up. For example, if I go out for a run on my own, I am likely to go low (no adreneline rush). BUT if I run a road race (5k, 10k, whatever), my BG goes WAY up because of the adreneline rush I get. The larger the crowd, the higher my BG goes. Same thing with things like thai boxing, crossfit, etc. For me, it has just been a lot of trial and error to find what works. For adreneline-packed activities, I usually bolus beforehand (espcially if I’m removing my pump) and then test in the middle. The ONLY problem is that if I complete my workout and I’m less than 110, I have to treat, because I will definitely go low an hour or so later. I only realized this after crashing a few too many times.

This is all so interesting. My 10 year old daughter was diagnosed on 4-15-11.
Her BG usually drops during exercise and occasionally
Stays the same if exercise is lt. Could this be because she is
Still in honeymoon phase? I’ve never heard of BG going up
During exercise though I have heard that stress on the body
Can raise BG.

Here is an article on diaTribe that Gary Scheiner wrote about exercise. There is a section for people that go with exercise. He suggests taking half of a correction bolus, but like Lila said, YMMV. I would not count on some fancy formula that your endork has working for you – like anything else with this disease, you need to test, test and test again to figure out what works for you!


I agree that it’s very different for different people, and any ‘equation’ out there is very hypothetical and to be used a guide only, until you figure out how your body works.

For me, even a brisk 30 minute walk can drop my blood sugar 100-150 mg/dl. I figured out that I ALWAYS have to drink juice beforehand, and afterwards I have to decrease my basal 20% for 5 hours. Other people wouldn’t drop that much even with an intense run.

Bernstein, "excercise... and blood sugar" in the index, explains this; the liver releases glucose in response to the exercise. (See the index; "How does excercise directly affect blood sugar?", pp 214-216 in my copy.)

My problem with strenuous excercise is more subtle; it very definately increases my insulin senstivity for about a day (say 24-36 hours.) That figure is the result of several hours hard physical labor. E.g. to quote a recent example loading about 30 90lb bags of ready mix cement into a cement mixer), but a day's hiking (about 4000 ft of ascent) produced a similar result in the past.

I have to drop my basal insulin substantially on the following day or I will have lows all day.

Yes ;-) I tried that once. I now have a cement mixer; I only have to lift the bags in. It's still hell. It is also extremely bad for the back.

But... I feel so-much-better (apart from my back) for the following week.

I recommend hiking.

Interestingly Bernstein emphasises the effect of excercise on lowering insulin resistance but doesn't, apparently, suggest that there is the short term insulin sensitivity I see. I'm just scanning Chapter 14 though, so maybe I missed it.

Kelly WPA’s link provides the counterpoint to Bernstein and the explanation of all this:


Thanks, Kelly WPA, for that link! It fits with everything I know, essential reading.