My EMG showed nothing, and the neurologists said they couldn't help me. Since then (5 years ago) I've read that small fiber neuropathies won't show on an EMG or regular nerve conduction test. I agree a skin biopsy would be useful I just read a researcher say it will become part of the small fiber neuropathy "testing gold standard".

For sure prediabetes can cause small fiber neuropathy, as well as mercury poisoning (or many toxins). Get a Dr. who knows about small fiber neuropathies (the Mayo clinic in Rochester has some). Also, Johns Hopkins has a great (they say) neuro department. Check online for small fiber neuropathy. Research is really taking off on this.