Background: The pathogenetic factors underlying development of diabetic polyneuropathy (DP) remain unclear. Reduced neurotrophic stimulation has been proposed as a possible mechanism. The neurotrophic factors IGF I and II, sCD-163, NGF, VEGF and BDNF are essential for development and regeneration of the nervous system. In earlier studies reduced concentrations of IGF-I and II in blood and reduced concentrations of NGF and BDNF in muscle and skin biopsies have been found in patients with DP.