hi Daver
During exercise a lot of different hormones come into play , which will alter your blood sugars. If you are working very hard Adrenaline and Cortisol are released which are the fight or flight Hormones and they alone raise Blood Glucose. Also your Liver will release Glucose as you work out as your muscles are putting in a demand for it for energy.
It is a fine balancing act trying to get the right dose of insulin to match your physical needs when exercising...it will all depend on how often you are exercising at what intensity on previous days to how your BG may react...a lot of things come into play. If you get a rise one day on the same amount of insulin to the same duration of exercise ,it may be that your muscles are still recovering from the afterburn of the previous days workout ,so are demanding more Glucose from your Liver ,and energy from your endocrine system to compensate for them being tired from the previous day.
If you have not had quiet as much insulin this will drive your BG up instead of the usual down you expect.
I run every day , have done for years and find that if I do a high intensity treadmill work out , my BG will go up instead of down due to working hard and fast . whereras a flat road run will keep a steady decline in Glucose....Hill runs will raise at first,then sharper drops at the 7/8 mile mark ,so I'm ready with glucose at this point...don't need that at all on a treadmill 12 mile run..With the same food every morning before a run and the same insulin dose...it's the intensity that alter the BG
This again is pretty predictable for me but I do have days just like you have said when it does something strange and unexpected ,as in it keeps raising and I have to correct during a race or training...this I have worked out is when my muscles are more tired from previous days training and I'm kicking out extra Glucose naturally.
Sorry for ramble, don't know if any of this helps...but it really is about testing experimenting and realising there are times during exercise when you may occasionally need to correct with insulin...Over the sessions you will see a pattern, and if you get a curve ball from time to time ,ignore it, they happen that's Diabetes and insulin :roll:
well done on the exercise and reducing your Basal, brill news