Our findings demonstrate that of the 232 proteins involved in ERS and unfolded protein response [56], only 11 ERS biomarkers have been measured in the serum of patients with T2D, and 6 (HSP70, GRP78, PRX1, PRX2, PRX4, PRX6, and SCGN) were consistently and significantly elevated compared with controls. Here, PRDX4 is linked to type 2 diabetes mellitus.