Table 1.
Summary of studies evaluating microbial and functional changes in individuals with T2DM.
| Sample Size | Age (y) | Sex | Technique | Microbiota Modifications | Functional Modifications | Study |
|---|---|---|---|---|---|---|
| 183 T2D 185 Controls (Chinese) |
13–86 | Women (153) Men (209) |
Metagenomic sequencing | Increased in T2D: A. muciniphila, Bacteroides caccae, Bacteroides Intestinalis, C. hathewayi, Clostridium ramosum, C. symbiosum, Desulfovibrio sp., Eggerthella lenta, and Escherichia coli Decreased in T2D: Clostridiales sp. SS3/4, Eubacterium rectale, F. prausnitzii, Roseburia intestinalis, and Roseburia inulinivorans. |
Increased in T2D: membrane transport of sugars, branched-chain amino acid (BCAA) transport, methane metabolism, xenobiotics degradation and metabolism, and sulphate reduction Increased in control: bacterial chemotaxis, flagellar assembly, butyrate biosynthesis, and metabolism of cofactors and vitamins. |
[23] |
| 53 T2D 49 IGT 43 Controls (Swedish) |
69–72 | Women (145) | Metagenomic sequencing | Increased in T2D: Clostridium clostridioforme, former-Lactobacillus gasseri, and Streptococcus mutans Decreased in T2D: Roseburia, Clostridium spp., Eubacterium eligens, Coriobacteriaceae, and Bacteroides intestinalis. |
Increased in T2D: starch and glucose metabolism, fructose and mannose metabolism, ABC transporters for amino acids, ions and simple sugars, fatty acid biosynthesis, and cysteine and methionine metabolism Increased in control: flagellar assembly, and riboflavin metabolism. |
[25] |
| 13 T2D 64 Prediabetes 44 Controls (Chinese) |
52–55 | Not available | 16S rRNA V3-V5 region | Increased in T2D: Clostridiales, Dorea, Prevotella, Collinsella, and Ruminococcus Decreased in T2D: Bacteroides, A. muciniphila, F. prausnitzii, Haemophilus parainfluenzae, and Roseburia |
- | [26] |
| 75 T2M 291 Controls (Danish) |
50–66 | Women (187) Men (179) |
Metagenomic sequencing | Increased in T2D: Prevotella copri and Bacteroides vulgatus Decreased in T2D: Roseburia, Bifidobacterium, Faecalibacterium, Oscillibacter, Coprococcus, and Butyrivibrio |
Increased in T2D: lipopolysaccharide and BCAA biosynthesis Decreased in T2D: BCAA transport into bacterial cells, methanogenesis, and pyruvate oxidation. |
[27] |
| 22 T1D 23 T2D 23 Controls (Polish) |
20–65 | Women (40) Men (28) |
16S rRNA | Increased in T2D: Ruminococcus, Enterobacteriaceae, and Verrucomicrobia Decreased in T2D: Bacteroides, Roseburia, and Faecalibacterium (n.s.) |
- | [28] |
| 20 T2D 40 Controls (Chinese) |
20–60 | Women (42) Men (18) |
16S rRNA V4-V5 region | Increased in T2D: Dorea, Fusobacterium, and F. prausnitzii Decreased in T2D: Parabacteroides, Akkermansia, Bifidobacterium, and Streptococcus |
Increased in T2D: butyrate production via transferase, methanol conversion, and pentose phosphate pathway Decreased in T2D: tyrosine degradation, leucine degradation, and anaerobic fatty acid beta-oxidation |
[29] |
| 98 T2D 193 Controls (Africans) |
41–70 | Not available | 16S rRNA V4 region | Increased in T2D: Desulfovibrio piger, Prevotella, Eubacterium, and Peptostreptococcus Decreased in T2D: Collinsella, Ruminococcus lactaris, Anaerostipes, Epulopiscium, and Clostridium |
Increased in T2D: proteasome pathway Decreased in T2D: none |
[21] |
| 134 T2D 37 Controls (Chinese) |
45–67 | Women (92) Men (79) |
16S rRNA V3-V4 region | Increased in T2D: Prevotella, Dialister, and Sutterella Decreased in T2D: Bacteroides, Bifidobacterium, Clostridium XIVa, Parabacteroides, Staphylococcus, Granulicatella, Porphyromonas, Clostridium XI, Blautia, Anaerostipes, Clostridium XVIII, Fusicatenibacter, Enterococcus, Clostridium IV, Eggerthella, and Flavonifractor. |
- | [30] |
| 46 T2D 75 CGI 178 IGT 189 IFG 523 Controls (Swedish) |
57–61 | Women (568) Men (443) |
Metagenomic sequencing | Increased in T2D: Coprococcus eutactus, Clostridiales bacterium, and Lachnospiraceae bacterium Decreased in T2D: Clostridium sp., C. hathewayi, Clostridium bolteae, C. symbiosum, and Roseburia faecis |
Increased in T2D: two-component systems, phosphotransferase systems, fructose and mannose metabolism, pentose phosphate pathway, bacterial biosynthesis of branched-chain amino acids, and metabolism of the B-group vitamins biotin and thiamine. Decreased in T2D: bacterial methanogenesis, glycolysis, peptidoglycan biosynthesis, vancomycin resistance, and DNA replication and transcription. |
[22] |
Abbreviations: y: years; n.s.: not significant. Bacteria: A. muciniphila: Akkermansia muciniphila; C. hathewayi: Clostridium hathewayi; C. symbiosum: Clostridium symbiosum; F. prausnitzii: Faecalibacterium prausnitzii.