Insulin activity is desensitised by cortisone, a hormone we produce*(unless you have addison's disease) in response to low level stress. So the more cortisone, the less effective each unit of insulin. The daily profile of cortisone varies across the day..
From a peak level of cortisone at ~1030am, it drops to 1/3 the level of the peak by 9pm
There a two sharp, temporary increases of cortisone at midday and 6pm.
Between 9pm and 3am cortisone remains at its daily nadir.
From 3am to 1030 cortisone levels rise peakinmg at 1030am.
https://www.researchgate.net/public...dvances_in_hydrocortisone_replacement_therapy
https://www.researchgate.net/publication
Working on this, I started to see if my insulin needs (T1D) were in acccord with these observations. Although I haven't finished yet, as takes a fairly assiduous recording of everything, I can say by and large, Yes. And some , no, maybe ;-). Well I hope that clarifies everything.
Just joking.
Yes, because if insulin activity is densensitised by cortisone, would you expect you need the biggest doses of insulin around 1030am decreasing to lower levels by 9pm. My settings are:
U/hr Time band Units
0.7 0000-0530 3.85
1.15 0530-1130 6.9
1.85 1130-530 11.1
1.55 530-1000 7
0.925 10-1200 1.85
(Note the time brackets are not equally long so the rate is a better a comparator.)
which sort of agrees with the study on cortisone levels.
However matters are complicated by how much variation one has from a 50:50 reported ideal ratio of basal: bolus delivery of insulin eg one use a higher basal to offset post eating highs. Or a high bolus ratio to limit insulin driven appetite, at risk of of high blood sugar short and long term effects.
I find I use ~60% basal to 40 bolus as I am trying to lower carb intake, but set my basal as low as possible in order to try to not stimulate appetite :-/ but high enough to (try) and avoid getting about 10mM at any stage. I not terribly succcessful, Its a matter of constant vigilance and sustaining microadjustments. Looking over carb and bolus insulin intake is hefty task so I get back when I completed it, if I ever complete it .