i have to admit i never asked myself this question..
what you need to know is that introducing an exogenous substance such as insulin and igf1 into your system will surely affect your normal recovery.
what you should also know is that if you don't take your insulin correctly you can suffer severe brain trauma or even die from hypoglicemia..so make sure you eat your sugar!!!
here is some great info on insulin
http://www.flexmuscle.net/forum/showthread.php?t=128