Increased arginase-1 activity in the RBCs of patients with Type 2 diabetes is associated with superoxide production and accelerated endothelial dysfunction (Yang et al., 2018; Mahdi et al., 2019; Pernow et al., 2019), suggesting a link between increased RBC arginase-1 activity and CVD. This evidence concerns the gene ARG1 and type 2 diabetes mellitus.