--this does sound like it might involve spinal problems caused by compression, , or as your wife mentions, central nervous system compromise (MS is a possibility, but there are other conditions that attack the spinal cord, such as acute disseminated myelitis) rather than a systemic metabolic, autoimmune, or toxic peripheral neuropathy, given what you wrote about onset and treatment. But, of course, symptoms of peripheral neuropathy can be exactly the same as those from central nervous system causes, which is why the investigation into causes is often long and very much process of elimination

Nevertheless, there is a whole protocol of tests for neurological symptoms--one of our members, with some input from others even put together one in a spreadsheet format (see [url]www.lizajane.org[url]) --what testing have you had besides that for diabetes? It would seem there should have been some MRI's of brain and spine done from what you've reported.