Compared with the NC group, the mesangial matrix index and the number of renal tubular infiltrating inflammatory cells were significantly higher in the DKD group (Fig 4E and 4F, P < 0.05); And the mesangial matrix index and the number of renal tubular infiltrating inflammatory cells were significantly lower in the Metrnl+/+ group compared with the Metrnl-/- group (Fig 4E and 4F, P < 0.05). Here, METRNL is linked to diabetic kidney disease.