A couple comments on this thread:
-Metanx is a prescription "medical food" that is intended to treat peripheral neuropathy. the active ingredients are L-methylfolate, methylcobalamin and pyridoxal 5-phosphate. Obviously, you can buy each of these over the counter if you wanted to. I have taken all those supplements in combination and it does seem to help. Later I stopped taking the high doses of P-5-P because other studies indicate it can actually cause PN for some people. Unfortunately, nothing works for everyone and for some people nothing seems to work. You just have to research and try things to try and hit on the combination that works best for you.

-There is some research that seems to indicate that it is possible for nerve damage to be done while people are still in the pre-diabetic phase. But just like much of the information related to PN, there is no definitive proof of this.