A variety of soluble growth factors influence the peripheral nervous system. Although of considerable importance during development and growth, they appear also to be implicated in tissue maintenance in adult life and, particularly, during nerve regeneration. In addition, cell-surface and extracellular connective tissue matrix molecules are intimately involved in regeneration. So far, the possible participation of such growth factors in the causation of diabetic neuropathy is only speculative, but there are indications that their use could be of value in treatment.