Metformin is indicated for management of Type 2 (not Type 1) diabetes. It works by blocking glucose production (a process called gluconeogenesis) by the liver.

While Type 2 diabetes is a risk factor for neuropathy, my understanding is that this is not a "given".

You and your friend might find the information in this (long) link about Type 2 diabetes helpful; http://www.mayoclinic.org/diseases-c...n/con-20031902 .