We took a look recently at http://www.diabetesdaily.com/wiki/Neuropathy – Diabetes support network – an online community forum. Here is their info on supplements for diabetic neuropathy; there seems to be the most data and dosage information on alpha lipoic acid:
There are 2 dietary supplements that have clinical evidence showing them to be effective treatments of diabetic neuropathy; alpha lipoic acid and benfotiamine. In several studies using a variety of dosages and routes of administration, alpha lipoic acid was found to reduce the various symptoms of peripheral diabetic neuropathy. A recent review of the published data determined “ALA should be considered as a treatment option for patients with peripheral diabetic neuropathy.” Also a recent study using orally administered alpha lipoic acid found that 600 mg once a day caused a marked reduction in the symptoms of diabetic neuropathy including stabbing pain, burning pain, paresthesia, and asleep numbness of the feet. Benfotiamine is a lipid soluble form of thiamine that has several placebo controlled double blind trials proving efficacy in treating neuropathy and various other diabetic comorbidities. 400 mg a day was the most commonly studied dose.