I have some question about this being related to your weight loss, as there appears (if my math is correct) to be a 6 year gap between losing the weight and onset of PN symptoms.

Is one side worse than the other? Has there been any imaging (x-ray, MRI, etc) to support the theory that it's related to your back? Back related problems usually affect one side more than the other, but it's not unheard of to affect both sides equally.

Do you know what your A1c's were before losing the weight?
What kind of work have you done?

Has any other testing been done (B12, D)?

The supplements I'd suggest (depending on testing, and because they're pretty much what I'm taking, and seem to be working for me) would be:

Balanced B (within reason-watch out for too much B6)
Benfotiamine 100 mg/day
B12 (methylcobalamin) 1000-5000 mcg/day; empty stomach
D3 5000 IU/day
C 500-1000 mg/day

R-Lipoic Acid (stabilized) 100 mg/day
B5 250-500 mg/day (these two work together; if RLA doesn't work, B5 may not)

These last two, if they work for you, may get you off the gabapentin (that would be my hope anyway)

I don't disagree with other suggestions. There's wisdom in trying one thing at a time to figure out if something works or not. OTOH, I know how it feels to want to stop/reverse this thing as quickly as possible, and some things aren't a bad idea to take anyway (within reason) if they support healthy nerves. My philosophy on this is If it can't hurt to try it, then it can't hurt to try it.

We have a lot in common— ~ageħ, age of onset, normal a1c, progression & timeline of symptoms... Feel free to send me a PM.

Doc