To minimize differences related to sample origin, an additional PCA was conducted, this time incorporating SNV normalization as a preprocessing step. In this analysis, PC1 and PC2 accounted for 56% and 16% of the spectral variance, respectively. The score values in Figure indicate that the samples do not cluster according to their origin, demonstrating that normalization effectively integrated both datasets. The clustering associated with the DKD class appeared less distinct compared to the non-normalized data, although the control samples were generally located in the upper left corner of the score plot. Notably, the loading in Figure (blue) shows positive bands associated with albumin alongside negative bands linked to glycoproteins and other metabolites naturally present in healthy samples. Furthermore, PC2 exhibited considerable similarities with the corresponding loading from the previous PCA analysis.