Fig. 2: IR-associated faecal metabolites are associated with altered gut microbiota and microbial genetic functions.

a, Co-abundance clusters of bacteria at the genus level and their abundance (n = 282). The participants were classified into four clusters, A to D, according to their taxonomic profiles. The proportion of individuals with IR are shown. Mid, intermediate. b, HOMA-IR, BMI, triglycerides (TG) and HDL-C levels among the participant clusters. c, Bacteria–metabolite networks of co-abundance microbial groups from a and faecal metabolites (n = 282). All faecal hydrophilic and bacteria-related lipid metabolites were included. Only interactions with positive and significant (P_adj < 0.05) Spearman’s correlations are shown. The metabolites in CAGs relating to carbohydrates in Fig. 1b are highlighted in red. Unclust., unclustered. d, The number of significant positive and negative correlations between genera and faecal carbohydrates. The top five genera in each correlation are shown. e, KEGG pathways relating to carbohydrate metabolism and membrane transport, faecal carbohydrates, the top three genera positively or negatively correlated with faecal carbohydrates, and the participant clusters. KEGG orthologues significantly (P_adj < 0.05) associated with the metabolite (left) and taxonomic abundance (right) are summarized as the percentage enrichment among KEGG pathways. The median percentage of 15 faecal carbohydrates (carb.) is shown in colour (blue to red) on the left, whereas the percentage enrichment is shown as the disk size on the right; the Spearman’s correlations between pathway-level abundance and six genera are shown in colour (blue to yellow) in the middle (n = 266). f, The abundance of representative KEGG orthologues involved in glycosidase among the participant clusters (n = 266). The abundance was transformed by arcsine square root transformation. The density plots in b and f indicate the median and distribution. Statistical analysis was performed using rank-based linear regression adjusted by age and sex (b; Supplementary Table 10), two-sided Wilcoxon rank-sum tests with multiple-testing correction (e; Supplementary Table 16), and Kruskal–Wallis tests with Dunn’s test (f; Supplementary Table 18). *P < 0.05, **P < 0.01, ***P < 0.001 in comparison to cluster C (with the lowest proportion of IR) (b and f).