I am an active 25 year old pump user who usually workouts about 3 times a week always in the evening after work or on weekend afternoons. I’ve decided to try and go to the gym in the morning before work in order to make it more likely that I’ll workout (I’m shooting for a 5 days/week average and evening plans always conflict with working out). I have gotten pretty good at managing my sugars around my PM workouts but when I switch and do the same workout (mainly cardio with a little bit of weights) in the morning I go high. I’ve done a fasting check of my AM basal and that’s good so it’s not a misdosing for the dawn effect on a daily basis.
This morning for example:
pre-workout - 158 (higher than I like due to a late night high last night that clearly wasn’t properly corrected)
no temp basal, no food, no bolus
immediately post workout - 218
I’ve been reading around and people have mentioned the dawn phenomenon as an explanation - that the cortisol your body churns out in the morning as a normal part of getting you started for the day can raise your BG. But why would exercise cause the cortisol to have more impact than on a non-exercise morning?
I’ve also read that it is due to the liver releasing stored glycogen. But it’s not happening with the same workout in the PM (or at least not to the same extent). What about the AM would cause the liver to release more and in the PM?
I am trying to understand the precise biological mechanisms at work here and any insight you might have would be much appreciated.