"He does have a problem with EXCESSIVE weight gain and now an insulin resistance problem,he takes another med for that."

Yet another sign that the child is lacking essential androgens is fat gain.  Androgens help to keep fat from being deposited in fat cells.  When muscle mass increases in growth, it needs more androgen to sustain it even in children their levels would raise a smidgen.  No androgen, no mass can be retained.  Less muscle mass, more fat storage.  They regulate fat and how it is used in the body.  

Excess ACTH also would force the increased need for insulin?  You have lowered cortisol levels which even though blocking androgens STILL causes the hypothalmus to make all the other hormones that come before the androgens such as ACTH.  That being released at higher amounts facilitates the need for a rise in insulin... higher amounts of that and you can more or less say here that this could possibly have caused the insulin resistance.

This is what I mean... so many knock on effects on other hormones in the body that are also responsible for growth.  They KNOW all this... that is what is SO frustrating.  Yet they try to block them completely in the hope that the child will grow and not gain weight? 

IMO:  Same problems, just another route to get to them with possibly MORE spin offs side-effect wise than controlling the child properly on cortisol.