As detailed in Table 1, among these studies of single or few biomarkers, some of the most frequently reported associations with DKD-relevant phenotypes are for biomarkers of inflammation and fibrosis pathways, such as soluble TNF receptors 1 and 2 (sTNFR1 and sTNFR2) [28–33], fibroblast growth factors 21 and 23 (FGF21, FGF23) [25, 34–41] and pigment epithelium-derived factor (PEDF) [42]. This evidence concerns the gene FGF21 and diabetic kidney disease.