For example, signalling via vascular endothelial growth factor (VEGF) appears important in mediating retinopathy in diabetes (reviewed in Wong et al., 2016), and hyperglycemia-induced up-regulation of GPCR signalling by the RAAS peptide, Ang II, has been reported in VSMCs (Montezano et al., 2014; Touyz et al., 2018). Here, AGT is linked to diabetes mellitus.