Thanks madisongirl for the useful link.

It was interesting to note that there were nearly twice as many pre-diabetic patients as there were diabetic that had been classed as idiopathic. This coincides with what some on NT have found.

One of the reasons that the causes of medication/chemical induced PN are not showing up in studies may be that the studies are taking so long to complete and post results.
Came across this article about the high number of institutes that are failing regularly to make public results - it could of course also be that the drug companies are trying to keep a lid on harmful side effects for as long as possible.

http://www.statnews.com/2015/12/13/c...investigation/