Need Advice on Basal Testing and Exercise

Hi all,

I’m wondering if anyone has any tips for conducting basal tests during a typical day that includes one or two exercise episodes. I ride my bike to/from work twice daily, logging 8-10 miles daily. I ride at a fairy brisk pace, burning a total of 400-500 calories during the 2 rides. I’ve been going low (sub-70 BG0 fairly often, between 2-4 times daily. I find I am having to correct the lows, which is messing with my diabetic diet (2500 calories, ca. 340 g carbs daily). I don’t set temp basal rates for the rides, as each ride is only 15-17 minutes long.

Since I am riding in the morning and late afternoon, I can’t follow the “normal” basal testing procedure that says “don’t exercise.” Does anyone have anything that works, or suggestions of what might work, in terms of figuring out some way of basal testing whilst in the middle of an exercise routine, or training plan?

Thanks in advance, Mike

Hey, Mike,
I had to smile when I read that you ride at a “fairy brisk pace.” Not that there’s anything wrong with that. Thanks for sharing.
I would suggest that you just ride as easy as you can. If you’re skipping breakfast, you’ve got more time to get to work anyway. Get your pace down to where it almost isn’t exercise.
There’s no perfect way to do basal testing if you’re not going to settle into bed or on a couch for the day. You can only do the best you can.
Could you do the testing on a weekend instead of workdays?

Well you do need a temp basal rate, because the exercise has long lasting effects on your body, as the glucose goes to the muscles to replace lost glycogen (i think that’s the reason.) If it were me, I’d lower my basal rate 2-3 hours in advance of the ride (because you want it to be lowered by the time you are riding) and I’d need to keep it low for most of the day or at least through lunch. Since you are low so often, try adjusting it by 5-10% at a time until you find that magic balance. You may also have to adjust the bolus calc too. After I exercise I reduce the amount I bolus by almost half. I constantly shift my basal and bolus rate based on how rigorous my exercise is. I find that you have to shift it well in advance of the activity and put it back to “normal” many hours later. that’s just me. But I like hard exercise and so it wouldn’t be acceptable to ease up on the exercise as a solution. There is a mathematical equation that will work for you, you just have to find it. In the greatest book I’ve read… “Pumping Insulin” there are some great tips for this.

A few other places you might go for information is the diabetes exercise and sports association. It is online at or the Adventures for the Cure guys. Adam Driscoll is a type 1 diabetic and an avid cyclist.


These other replies don’t seem to be in response to the question about basal rate testing.
I certainly wasn’t advising anyone to cut back on exercise. I was talking about what to do for one day of basal rate testing.

I’m way too late on this, but my opinion is that the purpose of basal rate testing is to test your basal rates based on normal activity and fasting. Normal activity for you includes biking to/from work, so I would just conduct the testing on a day/days you bike to/from work. If you are dropping too low to complete the test, you may want to go ahead and lower your basal rate for an hour or two before the usual time you drop low (if there is a “usual” time).