FGF23 and Marchiafava-Bignami disease: Among the four CKD–MBD biomarkers, FGF23 levels were significantly lower in DM group (462 [127–1790] vs. 1237 [251–3120] pg/mL, p = 0.028) and log-FGF23 independently predicted aortic PWV in DM group (β: 0.61, 95% confidence interval: 0.06–1.16, p = 0.029 in DM group; β: 0.10, 95% confidence interval: − 0.24–0.45, p = 0.546 in nonDM group; interaction p = 0.016).