Neurotrophic factors in the therapy of diabetic neuropathy.

A large number of neurotrophic factors that exert effects on specific neuronal populations in the peripheral nervous system have been discovered. Some of these factors may prove useful for the treatment of diabetic peripheral neuropathy. Among the most promising are members of the neurotrophin gene family (nerve growth factor [NGF], brain-derived neurotrophic factor, neurotrophin [NT]-3, and NT-4/5), insulin-like growth factor (IGF)-I and IGF-II, and glial cell-derived neurotrophic factor. Of these, NGF and the IGFs have been tested most extensively in animal models of diabetic neuropathy, with encouraging results. Recombinant human nerve growth factor (rhNGF) has been tested in phase II clinical trials for treatment of patients with diabetes, and the results have been encouraging. Phase III trials of rhNGF have been completed, and clinical trials of other neurotrophic factors are likely to be conducted in the next few years.