--that's not accurate at all--see my other post (with lots of references) on the possibility of neuropathy from impaired glucose tolerance that is not yet frank diabetes. (You might want to print out, of send the doc links to, a few of those--we do often have to educate the physicians.)

And, while the classic presentation of impaired glucose/diabetic neuropathy is, as Dr. Vinik says, of small-fiber length-dependent disruption, large fibers can be affected also:

http://neuromuscular.wustl.edu/nother/diabetes.htm