Objective To observe the characteristics of gut microbiota in patients with type 2 diabetes mellitus (T2DM) with different traditional Chinese medicine (TCM) syndrome types, and to further explore the key microbial communities and functional differences affecting syndrome differentiation.

Methods A total of 45 patients who visited the Department of Geriatrics, Hunan Provincial Hospital of Integrated Traditional Chinese and Western Medicine in 2023 were enrolled. These included 15 T2DM patients with qi-yin deficiency and blood stasis syndrome (Group A), 15 T2DM patients with qi-yin deficiency syndrome (Group B), and 15 non-diabetic patients from the same period (Group C). Fecal samples were collected, and 16S rRNA sequencing and analysis were performed.

Results 1) A total of 1564 operational taxonomic units (OTUs) were obtained from the three groups of patients, with 224, 127, and 351 unique OTUs identified in Groups A, B and C, respectively. 2) Both α- and β-diversity analyses indicated differences among the gut microbiota of the three groups. For instance, in the α-diversity analysis, the Sobs index showed significant inter-group differences (P < 0.01). Group A (264.00 ± 88.84) was significantly higher than Group B (145.90 ± 87.0) (P < 0.01), while Group B was significantly lower than Group C (229.7 ± 112.4) (P < 0.05). In the β-diversity analysis, the principal coordinate analysis (PCoA) indicated a clear separation among groups (R = 0.1610, P < 0.01). The R values in the Anosim/Adonis analysis ranged from 0.144 to 0.196, and the R² values ranged from 0.067 to 0.083, all indicating differences in inter-group comparisons (P < 0.01). 3) At the phylum level, Firmicutes, Actinobacteriota, and Bacteroidota were predominant in all groups. Among them, Bacteroidota exhibited significant inter-group differences (P < 0.05), with its abundance in Group A being significantly higher than that in Group B (P < 0.01). 4) Analysis of differences in microbiota composition, combined with linear discriminant analysis effect size (LEfSe) and Random Forest analysis, revealed that, at the genus level, the microbiota biomarkers between Group A and Group B were Parabacteroides, Bacteroides, g__unclassified_f__Lachnospiraceae, Roseburia, and Aspergillus, those between Group B and Group C were Erysipelotrichaceae_UCG-003 and Ruminococcus, and those between Group A and Group C were Parabacteroides, Anaerotruncus, and Oscillibacter. The results were validated by receiver operating characteristic (ROC) curve analysis, which suggested that the microbiota biomarkers between Group A and Group B (AUC = 0.91; 95% CI, 0.80-1.00), Group B and Group C (AUC = 0.84; 95% CI, 0.69-0.99), Group A and Group C (AUC = 0.87; 95% CI, 0.75-0.99) had good diagnostic efficacy. 5) The study identified 116 major pathways with inter-group differences through Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. For example, the enrichment degree of ABC transporter pathway in Group A (2.58 ± 0.36) was significantly lower than those in Group B (2.90 ± 0.48) and Group C (3.11 ± 0.66) (P < 0.05). These pathways were associated with metabolism and environmental information processing. g.

Conclusion The differences in the gut microbiota characteristics and functions among patients with specific TCM syndromes of T2DM may provide references for TCM syndrome differentiation and therapeutic mechanisms.