The significant hypersensitivity towards mechanical stimuli, regardless of the apparent loss of peripheral small sensory nerve fibers, as indicated by P2X3 and CGRP expression in the hind paw epidermis, coupled with the increased expression of activated microglia in the SDH of DM rats, suggests that the observed mechanical allodynia in STZ-induced DM rats developed via central sensitization. The gene discussed is P2RX3; the disease is diabetes mellitus.