Insulin peak time. "Activity" or "concentration"?

[kbountro]

Hi, I am trying to understand the role of the insulin model. What I struggle with is that the description of the variables indicate that, for example Fiasp's peak activity is 55 minutes. However, if we define activity as the glucose decreasing process, this is not true. This time is supposedly the peak concentration of insulin in serum. It is AFTER that time that the insulin works the best. There are clinical studies that report some figures regarding this (I read 115 min is an average peak activity for Fiasp).

I know the model is (primarily?) used to compute IOB. Can someone explain to me the benefit of assuming peak time = peak concentration time for this computation?

Thank you!