Extreme Lows

Hi -

While I’m doing any type of cardio, my blood sugar drops 100-200+ points in 15-30 minutes. I’ve tried lowering my basal, eating protein beforehand and drinking gatorade during. Has anyone experienced this or have any ideas on how to keep my BG up? It’s extremely frustrating, makes for some pretty short and pointless workouts. I will take any input you throw at me. Thanks in advance.


Lauren @laurenwatsek,

That is frightening! I’ve had my BG drop by that much but never that quickly - except twice when EMS had to be called to wake me. By how much do you lower your basal, and hoe long before exercise begins do you lower the basal rate?

When I bike ride, or even walk, I lower my basal to 25% a couple of hours BEFORE I begin peddling, and have it stayed lowered for a while after I finish. for instance, for a 2 1/2 hour ride, by basal will be at 25^ for 6 hours. And a half hour or so before finishing my ride I’ll stop, test and eat a 23 gram carb snack and take about 50^ of the estimated bolus amount; this is a “trick” learned to alert my body that my exercise is over and for it to stop, or slow down the production of glucagon.



I should add to the above, that when calculating any change in basal rate or any bolus, I look back at what I have been doing over the previous 12 hours [or anything unusual in the past day] and what I plan on doing. what I look at is activity level, any “non-routine” meals and all correction bolus, plus or minus, and basal adjustments.

Thank you so much for your input! Today I tried setting a temporary basal at 20% an hour before exercising. Started at 188, made it through my 30 minutes of cardio and ended at 91. Still a pretty significant drop, but I was able to push my intensity and finish before Hal (what I have named my pump) yelled at me for going below 80. I did one weight exercise before heading home where I hit 71. I ate a protein bar with 22 g of carbs, and my temp basal is continuing for the next 2 hours. My pump won’t let me decrease my temp basal any more than I have, so I’m thinking I may need to eat some kind of fast acting carbs during my cardio. Any ideas on that?

Thank you so much for your help!


You are narrowing the gap between before and after - but this is just one time so don’t get over confident. with me, I think I get a “problem” under control and the change works for several days and then, WAM - and for no apparent reason I go very low, or high.

Two suggestions:

  1. How long before exercise did you eat and bolus and is your ratio correct? Have you checked this recently.
  2. Is your basal rate correct for that time of day? You can validate and, if necessary, recalibrate your basal rates by fasting for long periods, testing frequently, and making adjustments. I do this a couple of times a year.


Glad it’s working out - I have to do the same thing, set a temp basal 30-60 minutes before for about 30%, and it usually works. Also after the exercise is over, I have to set another temp basal for about 70% for the next 2-4 hours to keep from going low after. This is the beauty of having a pump!

In my experience, what is more impactful to managing lows while working out is the mount of insulin on board (IOB). For example, if I start a run and I am 180, but have 5 units IOB, then I will be in trouble. If on the other hand, I am 180, but only a basal amount of 0.5 IOIB, then I will be O.K. So for me, I do not eat much before working out, which otherwise requires to cover with insulin. Start your workout a little higher (for me it’s about 180), but with not much IOB.

I have the same problem. I agree with the last response, if you have a lot of insulin on board then you will go low quick. Personally, when I do any kind of exercising, I always take off my pump or suspend it. I check my sugar about 15 min before I start, drink juice or eat like a 1/4 cup of oatmeal if I need to, and then go. 99% of the time I never get high because I like to push myself in the gym. Try it one time and see if it works for you. Just be careful not take insulin before you workout.