Table 1.

Gut microbiota changes in preclinical and clinical type 1 diabetes (T1D).

Subjects studied	Methods	Changes in gut microbiota	References
16 Caucasian children with T1D and 16 healthy Caucasian children	PCR-DGGE RT-qPCR	↓Firmicutes to Bacteroidetes ratio ↑Clostridium, Bacteroides, and Veillonella ↓Lactobacillus, Bifidobacterium, Blautia coccoides/Eubacterium rectale group, and Prevotella	(24)
12 Han Chinese subjects with T1D and 10 healthy Han Chinese subjects	16S rRNA gene sequencing	↑Bacteroidetes/Firmicutes ratio	(25)
4 children with beta-cell autoimmunity and 4 age-matched, genotype-matched, non-autoimmune individuals	16S rRNA gene sequencing	↑Bacteroidetes to Firmicutes ratio ↓Microbial diversity ↓Microbial diversity ↓Butyrate-producing species ↓Prevotella and Akkermansia ↑Bacteroides, Veillonella, and Alistipes	(26, 27)
8 Mexican children with T1D at onset, 13 children with T1D after 2 years treatment, and 8 healthy controls	16S rRNA gene sequencing	↑Bacteroides genus	(28)
Biopsies of the duodenal mucosa of 19 patients with T1D, 19 patients with celiac disease, and 16 healthy control subjects	16S rRNA gene sequencing	↑Firmicutes and Firmicutes/Bacteroidetes ratio ↓Proteobacteria and Bacteroidetes	(29)
15 children with T1D, 15 children with maturity-onset diabetes of the young 2, and 13 healthy children	16S rRNA gene sequencing	↓Microbial diversity ↑Bacteroides, Ruminococcus, Veillonella, Blautia, and Strepto-coccus genera ↓Bifidobacterium, Roseburia, Faecalibacterium, and Lachnospira	(30)
13 children at the T1D onset and 13 healthy children as control	PCR-DGGE RT-qPCR	↓Microbiota diversity ↑Bacteroides clarus, Alistipes obesi, and Bifidobacterium longum ↓Bacteroides vulgatus, oleiciplenus, coprophilus, and dorei	(31)
18 children with diabetes-associated autoantibodies, 18 autoantibody-negative children matched for age, sex, HLA-DQB1 genotype and early feeding history	16S rRNA gene sequencing	↓Lactate-producing and butyrate-producing species ↓Bifidobacterium adolescentis and Bifidobacterium pseudocatenulatum ↑Bacteroides genus ↓Microbial diversity	(32)
11 infants with diabetes-associated autoantibodies and 22 autoantibody-negative controls matched for gender, HLA genotype, and country	16S rRNA gene sequencing	↓Microbial diversity	(33)
28 children with new-onset T1D and 27 age-matched healthy controls	Human intestinal tract chip analysis	↑Bacilli (notably streptococci) and the phylum Bacteroidetes ↓Butyrate-producing species within Clostridium clusters IV and XIVa ↑Microbial diversity	(34)
73 children and adolescents shortly after T1D onset and 103 matched control subjects of similar place of residence and age	16S rRNA gene sequencing	↓Clostridium clusters IV or XIVa ↑Escherichia ↓Eubacterium and Roseburia	(35)
53 adults with longstanding T1D without complications or medication and 50 healthy controls matched for age, sex, and BMI	16S rRNA gene sequencing	↓Butyrate-producing species	(36)
20 patients with T1D and 28 healthy control subjects	16S rRNA gene sequencing	↑Bacteroides vulgatus, Bacteroides rodentium, Prevotella copri, and Bacteroides xylanisolvens ↓Bifidobacterium and Roseburia	(37)
Fecal protein collected from 3 T1D children and 3 control children	Combination of two-dimensional gel electrophoresis and spectral counting	↑Clostridial cluster XVa and cluster IV and Bacteroides ↓Bifidobacteria	(38)
35 patients with newly diagnosed T1D and 35 healthy subjects who were randomly selected and had similar demographics	Stool cultures	↓Bifidobacterium ↑Candida albicans and Enterobacteriaceae other than Escherichia coli	(39)
42 patients with newly diagnosed T1D and 42 healthy subjects	Stool cultures	↑Candida albicans	(40)

PCR, polymerase chain reaction; DGGE, denaturing gradient gel electrophoresis; RT-qPCR, real-time quantitative polymerase chain reaction.