NGF and diabetes mellitus: According to our data and to the theory of DPN as a biphasic process, characterized by two distinct developmental stages [1], the NGF could assume a double role: in the first time of diabetes development it could actively participate in the establishment of neuronal sufferance and of the hyperalgesic symptoms; in a late phase it could be of therapeutic value, being able to support suffering DRG neurons and reestablish impaired sensory functions.