This has been the one area where I feel I am getting ahead of type 1.. but it is very individual thing. For me the key has been heart rate, not about how many bpm but getting it up and including max to see what happens to the blood values. The libre has allowed me to try this out..
A steady cardio session, this is me... other people's bodies will no doubt react differently, you might well see a significant rise in glucose levels. My guess is the body recognises a rise in demand and tries to feed it, but unless the muscles are working hard they won't take in all the available glucose hence the readings will stay high. I see this up to something like 75% of max, on a stationary bike and an octane zero runner ( not a treadmill but kind of running) .. it's when the muscles begin to demand more, the heart rate goes up and the glucose levels drop quite rapidly. I have to move weights for work, sometimes 3-5 tons in a day.. really, lots of 10 and 20 kg weights moved on and off of scales, I am finding that this eventually lowers the bg but over a long period of time unless I am walking some distance between where the weights are and where the scale is, again if the whole body is used and the heart rate can be raised, this drops the bg.
For now it will have to be a steady trial and error thing, firstly to get used to the different machines and stresses of them. A scan of the libre as often as you/she likes but not more than perhaps 15 minutes apart until you can see the patterns developing. I am comfortable with 30 minutes scans now but I would measure every 5-10 minutes before.. don't be surprised to see high readings but, essentially, keep dextrose or some very quick acting sugary item within arms reach.
For what its worth, I am not comparable to your daughter other than we have type 1 in common, I exercise with no fast acting insulin on board.. all my exercise is cardio because I simply don't want to lift anything more after some days at work!
Hypos during exercise I suspect won't be an issue until she gets to a point where the intensity is high, but that is why you will have something very nearby just in case.. the libre will guide you..afterwards it is a very good idea to keep scanning as if still exercising for at least an hour. And eating afterwards is easier small and often rather than a bolus injection and a sit-down meal.
A night time hypo is possible. I keep my basal insulin the same, or as near the same, at all times.. if I have exercised particularly over an extended period, I watch the bg closely, I want to see a slightly upward trend as a reaction to the small and often eating, and will eat a small amount of a slow acting carb before I go to bed.
This is still work in progress for me, and again your daughter will have her own reaction to what she is doing. Her targets and motivations and preferences will all change.. you/she should be looking for the patterns that the libre will provide. No short cuts unfortunately..!
Hope there is something of use to you in that. But enjoy, I find that I have a feeling of beating diabetes when I have not injected for hours and I am eating (sensible little pieces of non-challenging food..) and keeping my body working.. ok, the diabetes is there waiting when I stop but for a few hours I am beating it..
