Fig. 6

Longitudinal study of associations between D-amino acids and kidney function. The plasma D-Ala (a) and D-Ser levels (b) of all patients with CKD. Box plots use horizontal lines to indicate the median, 25th, and 75th percentile values. D-Amino acid analysis of all patients with CKD (c). D-Amino acid and D/L-amino acid analysis in patients with DKD (d). The length of the bars indicates the statistical significance, and the color of the circles at the ends represents the direction of eGFR change associated with the amino acids, whether positive or negative. For example, in (c), the D-Ala bar shows a red circle at the end of a long bar, indicating that individuals with higher D-Ala levels had a significantly slower eGFR change (p < 0.0001). *p < 0.05, ***p < 0.001, as analysed using one-way ANOVA. CKD chronic kidney disease, D-Ala D-alanine, DKD diabetic kidney disease, DM diabetes mellitus, D-Ser D-serine, D-Ala D-alanine, eGFR estimated glomerular filtration rate. *p < 0.05, **p < 0.01, ***p < 0.001.