This study aimed to investigate the relationship of four chronic kidney disease–mineral and bone disorder (CKD–MBD) biomarkers, including intact parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), soluble klotho, and fetuin-A, with aortic stiffness in peritoneal dialysis (PD) patients, comparing those with and without diabetes mellitus (DM). The gene discussed is KL; the disease is diabetes mellitus.