The present investigation aims to identify the potential associations between the metabolites detected in serum and urine, previously characterized by untargeted ultra-high-performance liquid chromatography coupled with electrospray ionization–quadrupole–time-of-flight mass spectrometry (UHPLC-QTOF-ESI+-MS) and quantified through targeted analyses, and corresponding inflammatory biomarkers (interleukins, TNF-α, TGF-β) identified in the serum and urine of patients suffering from T2DM and DKD. Here, TNF is linked to diabetic kidney disease.