Let me rephrase. If he wants to get as much benefit from insulin as he can, while still maintaining a normal level of insulin sensitivity, he will not only need metformin, but several other insulin sensitizers as well. If he is also using GH, he is going to need it all the more.
So, my recommendation was directed towards those people who wish to take full advantage of insulin without damaging their metabolic health. Many insulin & GH using BB'rs are severely insulin resistant...and no amount of leaness is going to correct it. Unfortnately, GH and insulin, when used at even moderate BB'ing doses, can cause insulin resistance. The higher the dosages the worse the problem gets.
I would never recommend using insulin or GH or the point of insulin resistance...and if the BB'r wants to use higher dosages of these 2 drugs than what the body will tolerate (tolerate= maintaining normal sensitivity), then insulin sensitizers are going to have to play a role. The right combination of sensitizers (supps & drugs) used properly can work wonders for increases sensitivity.