TRPV1 and diabetes mellitus: Transient receptor potential vanilloid 1 (TRPV1), also known as the capsaicin receptor, is mainly distributed in medium- and small-diameter neurons of the DRG and the trigeminal ganglion (Kaneko and Szallasi, 2014) and plays an important role in enhancing of pain sensitivity caused by heat and chemicals in a model of diabetes-induced NPP (Gunthorpe and Szallasi, 2008; Hsu et al., 2014; Zhang et al., 2020).