The activation of BDNF-TrkB system can be a link in the development of hyperalgesia, obesity, and inflammation in painful form of diabetic polyneuropathy, and this connection is most likely made by phosphatidylinositol-3 kinase/Akt (PI3K/Akt) signaling pathway. The gene discussed is AKT1; the disease is obesity due to melanocortin 4 receptor deficiency.