Cardio specific question

I need help from people that to cardio please.

For the past week the same formula happens. I go into a 60 minute cardio class at around 120. I turn my pump off 10 minutes before class and drop down to 70 with my Dexcom arrow pointing straight down 1/2 way in. I then drink a juice box with 10g of sugar and come up to about 100 for the rest of class. When I leave class my BS goes up to 200/250 and I wing it with temp basals/bolus, etc…

I need help!?

Hi Molly,
That 50 point drop early on is fairly normal when going from rest to activity. Blood glucose is the most readily available form of fuel your body has, so it immediately pulls that from your blood before the other fuel sources - lipolysis and muscle glycogen - are put into play. That is what causes the early drop.

You can help reduce that early drop by doing two things. Take a few carbs right before you start, and turn off your basal a little earlier than 10 minutes before.

The spike afterward might be from either the juice carbs, or it might be from exercise intensity. If you are doing a hard finish and your heart rate rises to a certain level of intensity, your body will release cortisol which will cause your liver to release fuel for the energy that you are using. It is very much like the fight or flight response.

If you are spiking predictably, you can turn your pump back on a little before the class is over, or just bolus a little before the intense section of the exercise.

Possibly, reducing that early drop and not needing as much juice in the middle of the class will also help reduce the spike that happens afterward.


This is gonna be tricky. I would urge you to NOT assume that you see the same pattern of BG everytime. Exercise caution, the pattern may change in a month. If that happens, I don’t want it to catch you by surprise.

I tend not to do many adjustments with my pump during exercise and just treat with sugar. But, I get very erratic numbers.