POSTN and diabetic kidney disease: Table 2 demonstrates positive correlations between periostin levels and clinical/laboratory parameters, including the, creatinine, diabetes’ period, ACR, HbA1c and both RRI and PSWE values (p < 0.001) (Fig. 1A and B), and negative correlation with eGFR, emphasizing periostin’s reliability as a biomarker for worsening kidney function and fibrosis in DKD.