Another reason for giving newly-diagnosed Type 2s metformin straight away is if they are obese, like me.
I asked my GP for Metformin for weight loss about 3 months after he had diagnosed me but while I was still in denial and refusing to let them register me. I admitted to insulin resistance but believed I could turn things round by diet and weight loss. He gave it to me, and I think he got into trouble with a senior partner for doing so, as I believe it is only licensed for the treatment of diabetes.
It seems unless you are registered as diabetic, it shouldn't be prescribed.
Viv 8)