I don't think it matters nearly as much as people would have you think.
For growth you need two things IMO:
1. To get stronger on your lifts. I don't care what program your using, if it does not focus around Progressive Overload one way or another, it's not going to get you very far.
2. To eat/rest/recover enough.
Nutrition is a general thing. Recovery is a general thing. Shoot, getting stronger is a GENERAL thing! It effects the entire body.
The only thing you can monitor is your strength increases, and whether your getting 'fatter' or 'buffer'.
Don't worry about insulin. Just lift, eat, sleep.
Behold, I say unto you, many are called, but few are chosen.....