What do you do when you exercise?

Hi Everyone!

I have been having problems when I exercise. Sometimes my blood sugars go up and somtimes they go down. I was wondering what others do when they exercise and if anyone has any tips to keep the blood sugars from rising or lowering too much

I am a type 1 and I would think this would be a totally different issue for type 2s.

I see that you are using a pump. With the pump, I turn down my basal rate (using a temporary basal rate) to 50% one hour before I exercise and leave it turned down for two hours. If it’s in the evening, then I leave it turned down for six hours cause I get lows during the night if I exercise if the evening. Hope this helps!

I recently started exercising and have read a bit about it, from what I understand depending on how intense the exercise is you may be getting a liver dump. It does this to feed your body during the exercise. Try only doing low level exercise for a bit like walking for half an hour and see if that causes the highs.

I only turn my basal down if I’ll be exercising for over an hour. Otherwise I leave it alone. By any means, don’t turn it off.

Blood sugars can sometimes rise after exercise because you’ve used up all your glucose and your liver starts pumping out ‘emergency’ supplies. It’s helpful, therefore, to start with your BG a little on the high side, even up to 200.

If you BG is normal when you start, try ingesting some carbs first, just 15 to 30g.

Most of all TEST. Test before, test every 30-40 minutes and test after. It’s the only way to see what’s going on. After awhile you’ll know how your body reacts and you’ll get the hang of it. I’m constantly adjusting.

Also, keep lots of water and fast acting carbs, like glucotabs, on hand.

Take a look at the book The Diabetic Athlete by Sherri Colbert.

Thanks Kristen,

I have to say I tend to have more problems with highs than lows during exercise and really don’t experience lows afterwards at all. If I experience lows it tends to be during but like I said it is more often highs.

What is your blood sugar typically when you start exercising?

Thanks for sharing?

Did you find the book the Diabetic Athlete helpful?

I have been exercising for years. well I have had diabetes for 17 years and probably have been exercising regularly for half or more of that time.

Anyways, I used to try to get my blood sugars to 180 to 200 before my workouts to prevent lows but now I am really trying to get my numbers down mainly to prepare for pregnancy and for pregnancy 180 or 200 is considered really high (which I have to say is shocking to me because I used to consider that okay not great but not aweful). Anyways, I want to be able to exercise when I am pregnant as well as keep my blood sugars within target so I want to fine tone this exercise issue before I start trying to become pregnant.

I am so in the same place, Jacki. Pushing for those 180-200 range starts worked better than temp basal adjustments for me, but my A1C is affected by them.

Like Terry said, you can continue to rise post-workout. My endo said that many diabetics on insulin pumps will reduce their basal insulin rates both an hour before and an hour after they work-out. For a non-insulin user, you might test just after and then again an hour later - to see where it was and that it has dropped acceptably.


If you don’t feel like you’re going low when the lawn is done, go get some ice tea and sit in the shade for 10 or 15 minutes before you test.

That’s what I’d, do, anyway! :slight_smile:

I have “The Diabetic Athlete” but find it too detailed to do me much good. It’s a tough read unless you’re really into biomedical detail. I did manage to glean a few things from it and other exercise blogs. Here’s my 2 cents.

First, the rising blood sugars are typically due to extended anaerobic exercising. If you don’t have one, I would suggest getting a heart rate monitor. They’re a tad pricey, but very valuable. Do some searches on identifying your aerobic heartrate zone. There are some simple formulas based on age that will get you started. Don’t go above your aerobic zone. This is probably what’s giving you the highs (if you’re not dialing down your basal).

My typical aerobic workout is 60 minutes with a target heart rate between 140 and 150. I found this range as the result of a stress test. It will sound high if you look at the age formulas, but it’s the right range for me. I dial my basal down to 20% 1-2 hours before I exercise. I also let it return to normal 30 minutes prior to finnishing. My target starting BG is 160-180. Yeah, it sounds high, but I know it’s going to come down within the next hour. Depending upon how long I’ve had my basal dialed down or if I have the tail end of a bolus on board, my BG can drop like a rock during exercise, so I test every 15 minutes. If my BG hits 100, I dring 22g of carbs via Gatorade. However, if I drank a Gatorade 15 minutes ago, my BG’s above 60 and I only have 15 minutes left, I usually don’t drink another one. That’ll put me high shortly after I work out. Test again 30-60 minutes after you finnish your workout to try to catch an upward trend. If you have one, try to figure out what’s causing it and adjust.

As you can see, most people’s problems are low BGs, so we’re all playing with dialing down basals and suplimenting carbs. If you’re not dialing down basals, you’re not suplimenting carbs and you’re still going high (sounds very odd), but you’re probably working in an anaerobic zone, which you don’t want to do for any length of time anyway, unless you’re a hard core athelete training for an event, and even then, there are rules to how much time to train anaerobically.

I hope this helps.

Come to think of it, a lot of cardio equipment these days have heart rate monitors built into them. You’re just forced to keep your hands on some metal plates. You might just give this a try for a few weeks and see how it goes.

Mike & Terry, do you worry that the 160-180 pre-workout range skews your A1C or do you think the benefits of a healthy workout are such that it doesn’t have an effect? I have tried the technique with success, but that concern keeps me skeptical about it as a personal habit.

Hi Jacki! I think it probably depends on the kind of exercise you’re doing. When I’m lifting (and I lift with the men…), I occasionally experience highs that we think are due to the glucose stored in my muscles being released. I also experience low rebounds (liver dumps) if I drop during exercise and don’t stop to treat it (I have asymptomatic lows, so I don’t always know they’re happening…). I usually turn my basal down during exercise by about 40%, just during the duration. I also check my bsg right before and eat (with a normal meal bolus) right after.

If I’m doing cardio, I still turn it down, but tend to experience more dramatic lows right after. Again, 1/2 a peanut butter and jelly sandwich with a lower than normal meal bolus usually takes care of it.

I find that I continue to burn at a higher metabolic rate after exercise for several hours. Sometimes I don’t bolus for dinner due to the impending lows.

Hope this helps you some!

Very good advice! I had an “AT” test done by my trainer at the gym… Finding your anaerobic threshold is not that complicated, but have someone with you when you do it…

Get on a treadmill with a heartrate monitor (most gyms allow you to use theirs for free!), set it at a ridiculous incline and a reasonable pace (12 incline/ 2.5 - 3 mph) and go until you can hardly breath or talk (that’s what the friend is for… Keep you talking). Check your heartrate. That’s where you’re working anaerobically. Typically you will drop it 10 beats per minute to be working at your optimum aerobic zone. For me, I hit anaerobic at 143 bpm. My training zone is 135 bpm for maximum fat burning. In your zone, you should feel like you can go for an hour. At your threshold you should feel somewhat like dying :wink:

Hi Melissa. No, I’m not worried about a temporary bump to as high as 200. Given the choice of a temporary bump or not working out, I choose the former. Perhaps someone with more medical background than I can be more precise, but I believe your A1C is measuring sustained highs. This also is where your health risks come from. Temporary, short highs, I don’t believe, are a problem, and I don’t think they’ll even be reflected in your A1C.

I suppose, if you really want to dial it in, you could figure out your carb intake requirements during exercise and how fast the carbs will convert and start with a lower BG, but I don’t know anyone who realistically does that. It’s some pretty precise calculations, precise management and the hormonal variables you can’t control will probably drive you crazy.

From Val’s comments, this is a great way to get a more realistic target heart rate zone. I did my “poor man’s stress test” on a spin bike. You just want to make sure you warm up at a comfortable pace for 10-15 minutes. Then every minute, increase the intensity and watch your heartrate. When your heartrate stops increasing despite increasing your intensity several times, you’re there. Keep in mind that this is very taxing for your body and you should plan on recovery the rest of the day. Although I did a spin class afterword. oops. Again, there are formulas for your aerobic zone that are basically a percentage of your max heart rate. I don’t remember the actual percentages, but they should not be hard to find.

If you’re really training hard core, I think the rule is still not to train any more than 10% of your time in your anaerobic zone. I don’t train in my anaerobic zone at all.

Hi Mike, I don’t train in my anaerobic zone either. Even when I’m leaning out for a physique competition. And, I agree with you (though I’d never thought of it before), I tend to spike only on the rare occasions that I hit the anaerobic zone. Otherwise, I tend to run lower during and post workouts. The lower temp basal does stop the spike whether it’s from muscular glucose stores or liver dumps whatever the case may be… I actually wish I knew which it was. And, the lower temp basal definitely prevents post workout crashes!

It’s a really hard thing to work through… All of our bodies work differently. If there was a formula that worked for everyone, we’d all be under 6’s with our A1c’s :wink:

Also, I usually try to avoid workouts if my bsg is not above my target. I usually try to keep it right around 160 pre-workout. That usually works well for me…

I have been exercising for a long time and almost always go very low during the aerobic exercise. So like the others, I lower my temp basal during the exercise but try to set it so it ends 1/2-1 hour before I am done. As soon as I stop, my liver wants to help me replenish my glucose stores so since I take Symlin at meal time, I use just a small dose of it as soon as I stop exercising to prevent that and that has worked well for me. Before I was on the Symlin, I would automatically give myself a bolus of insulin as soon as I stopped exercising in anticipation of that rise in BG but sometimes it didn’t work out so well and I would go low. Basicall, I guess you just need to keep trying to figure it out. Hope some of these suggestions work for you.

Interesting. So you take symlin after you exercise to prevent your blood sugar from rising? Is that correct?