Im a little confused with what exactly you mean but maybe if i tell you some of my experiences with giving myself insulin itll clear some things up for you.
First of all, i give myself two types of insulin. A "bolus" insulin which is fast acting and i take before meals based almost exclusively on the amount of carbs in the meal. There is also a "basal" insulin, lasting 24 hours that i take before i go to bed to counter the constant internal glucose releases mostly by the liver.
Im not completely sure of this but I think normal people dont have constant internal glucose releases. Anyways, ive noticed that the lessening of the amount of insulin i need post workout is not a sensitivity change but a block drop, as in an absolute number worth a certain amount of grams of carbs. One time I did eat a post workout snack that consisted of only the block drop so I took no bolus insulin.
My blood sugar was too high a little after the meal, but when I woke up the next morning (I had trained at night) my blood sugar was just where I calculated it would be. So, insulin is needed for this drop to happen, it just took a long time because the basal insulin just has a little action at any given point in time.
On a separate equation I had a big ass burrito for lunch that fucked up my blood sugar, so i took some more insulin about two hours after I ate, then went and trained about an hour after that. The thing is when I finished training the extra bolus insulin I took to correct the high blood sugar was still exerting a pretty big effect. My blood sugar crashed hardcore within twenty minutes of the end of my workout because of that insulin. I would guess that your body just really wants some glucose after workouts, and fast lol.
The other cool thing is that if you train consistently at the same time several days a week then you will have increased insulin sensitivity at that same time of day even on days you dont train.