If you knew your A1C that would help decide about a long GTT test.

Gluten is in wheat and rye products. It can cause burning.

Another dietary thing I found for myself was potatoes. (and some tomato products). Solanine in potatoes, seems to be difficult
for some people to tolerate. The burning can happen a day or two after eating a potato product. So it is hard to pin down.

But nightshade veggies are difficult for some people. You can go on an elimination diet and not eat any peppers/potatoes/tomatoes for a month, then reintroduce one here and there and see if your burning goes away, then returns.

Also burning seems to be worse when the tempertures go up seasonally.

Have you had testing for B12 and Vit D levels? Those are often low in many people, and it helps to fix them ASAP. Then you can decide about other things.

I am not aware of high biotin affecting neuropathy. Biotin is a factor that helps mitochondria work better.

Here is a monograph on Biotin.
http://lpi.oregonstate.edu/infocenter/vitamins/biotin/