Likewise, proximal tubule markers including the sodium–hydrogen exchange cofactor 3 (PDZK1, 4.2-fold decrease, p = 1.9 × 10−5) and the sodium–phosphate cotransporter (SLC34A1, 3.2-fold decrease, p = 8.1 × 10−4) were down-regulated in DKD, likely reflecting chronic injury. This evidence concerns the gene PDZK1 and diabetic kidney disease.