It's a little late - but I have recently been doing Hot Yoga (same as bikram but not one of his teachers) and my bgs are going through the roof. I need to be more consistent in the analysis; however, I will wake at 115 and after class 250. I have tried to bolus a bit before and remove it - thinking it might cook up the insulin. but not really having too much luck. looking for anyone else that's tried / had success.
I am not on a pump but have had the same experience with BG surging during hot yoga. I often go up 50-60 points from the workout, but the only times I have tried to take insulin before class I have crashed. No winning there!
Unlikely the insulin is being defacto "boiled", if so your readings would be high everywhere, as the chemical bonds would get broken by the high heat caused by heating the insulin even once.
Far more likely would be adrenaline caused by the adrenaline response caused by the dynamic asana being done that vigorously. Used to get high readings doing certain asana, head stand, etc., figured out i was using too much strength, effort and was getting adrenaline from doing them way too hard...
Controlled the effort lost the spike hours afterwards...
I do Bikram yoga regularly and use CGM. IV-3000 is good to keep the sensor on my tummy. It's pretty good (however, after having false-hypo, I decided to not to bring the transmitter to a classroom since it keeps buzzing)