PTH and diabetic kidney disease: During empagliflozin treatment, there were significant positive linear correlations between the changes of serum FGF-23 and TmP/GFR (r = 5174, p < 0.001), BAP and TmP/GFR (r = 9587, p < 0.001) and PTH and TmP/GFR (r = 6876, p < 0.001) in the whole study group positive linear correlations were also observed between BAP and TmP/GFR both before and after empagliflozin therapy in both subgroups, i.e., in ND-CKD: (r = 8681, p < 0.001 and r = 8596, p < 0.001, respectively), and in DKD (r = 9532, p < 0.001 and r = 9480, p < 0.001, respectively).