Welcome, to Neurotalk!!

Being that Diabetes is one of the most common causes of both PN and autonomic neuropathy, your thinking is right in line.

It is, in fact, quite possible to have symptoms even with just pre-diabetes. Symptoms will appear as soon as the nerves are damaged and it doesn't take much in the way of high blood glucose to create that damage.

Therefore, I would start with a 3 hour glucose tolerance test and serum A1C. This will give you a better idea of your blood sugar level.

You mention toxic...what substance have you taken that might fall into the category? There are many toxic medications that are known to cause PN...statins, antibiotics, chemo, etc. So the more info you give us, the easier it is for us to help....like any illnesses that occurred just prior to your symptoms, other medications you take...and so on.