How come your levels go up with exercise? Or more accurately how come hers go down!? It’s like watching a battery drain down. Literally 15mmols to 5 in 20 minutes!!
The way I understand it, there are two things that happen during exercise that affect our BG
- our liver dumps more glucose to give us the energy we need
- our body because more efficient at using insulin
The second point takes a bit longer to kick in. So, if we were doing stop-start kind of exercise (like playing a team sport where we have short spurts of running followed by a minute or two of waiting for the ball to come our way), the liver dump happens but the insulin efficiency less so.
And, of course, other things that affect our BG when we are not exercising do not stop. So, the stress of losing or having your team mates relying on you or seeing another rugby player charge at you, will cause more liver dumping.
I don't play competitive sports but I can see the difference when I cycle.
- if I pootle along a flat tow path chatting to my mates, there is little impact to my BG
- if I go flat out at a Spin class for 45 minutes, my BG plummets.
- if I slog up a steep hill against the wind and rain, my BG rockets.
As different exercise has different effects to BG, I struggle to understand the "exercise mode" on HCL. I use my pump in a manual mode so need to make the adjustments to basal myself. I have different temporary basals depending up on what I am going to do (annoyingly I need to make the basal change before I start exercise)
- if I am Spinning, I suspend my basal
- if I am climbing, I increase my basal by 30%
- if I am hiking for 3 to 4 hours, I reduce my basal by 50%
- if I am walking to the shops, gardening, doing the housework, ... I don't change my basal
These basal changes are personal. I know others who need to reduce their basal for the last category.
But, I imagine the exercise a young girl does is more like constant running around which is closer to the Spin class for me.
Edited to add: as insulin is much more efficient when exercising, it is also important to consider Insulin on Board (IOB). I try to avoid bolusing 4 hours before exercise. Or, if I am bolusing for food, I significantly reduce it if I am about to exercise.
If I did a Spin class half hour after lunch with my usual bolus dose, I would not be surprised to see my BG plummet 6 mmol/l in 15 minutes. Not sure if I would expect it to drop from 15 mmol/l but then, I would never trust 15mmol/l on a CGM - they always overegg highs for me so I always check anything higher than 10mmol/l with a finger prick.