Previous studies indicated that malnutrition and micro-inflammation, oxidative stress, endoplasmic reticulum stress, metabolic acidosis, vitamin D deficiency and secondary hyperparathyroidism, depressed serum erythropoietin and anemia, and suppressors of cytokine signaling all cause IR by suppressing insulin receptor-PI3K-Akt pathways in CKD [27]. Here, EPO is linked to vitamin D deficiency.