Unlocking the secrets of the human gut microbiota: Comprehensive review on its role in different diseases

Table 3 Overview of gut microbiota’s role in diabetes and mechanistic insights

Sl No.	Disease/drug target	Mechanism of involvement	Key bacteria or drug implicated	Ref.
1	GLP-1 receptor agonists	Mimic the incretin GLP-1, enhancing insulin secretion, slowing gastric emptying, and altering gut microbiota composition	Decreased: Allobaculum, Turicibacter, Anaerostipes, Blautia, Lactobacillus, Butyricimonas, Desulfovibrio, Clostridiales, Bacteroidales. Increases: Akkermansia muciniphila	[67]
2	Insulin	Improves glycemic control by increasing glucose uptake into cells. Minimal direct impact on gut microbiota	Minimal direct effect on humans. In rats, it increased Norank_f_Bacteroidales_S24-7 and decreased Lactobacillus and Peptostreptococcaceae, suggesting possible effects on gut bacteria in animal models. Effect on T2DM: Influences microbiota dysbiosis in T2DM patients, potentially regulating inflammation and gut health	[68]
3	Metabolic syndrome	Increased intestinal permeability leading to systemic inflammation; effects on metabolic pathways and mood	Increased: Lactobacillus spp., Bacteroides spp.	[69]
4	Obesity	Gut microbiota affecting metabolic processes and inflammatory responses; alterations in appetite regulation and mood	Increased: Firmicutes spp., decreased: Bacteroidetes spp.	[70]
		Metabolic dysregulation, energy extraction from diet	Increased: Bacteroides, Firmicutes	[71]
5	SGLT2 inhibitors	Inhibit SGLT2 in the proximal tubule, preventing glucose reabsorption and promoting glucose excretion in urine. Limited impact on gut microbiota reported	Dapagliflozin is used as drug. Ruminococcaceae, Proteobacteria (Desulfovibrionaceae); Sotagliflozin changes in Firmicutes/Bacteroidetes ratio with high-sucrose diet	[72]
6	Type 1 diabetes	Altered microbiota composition influencing the immune system and glucose metabolism	Decrease: Prevotella, Akkermansia. Increase: Actinobacteria, Bacteroidetes, Proteobacteria, Lactobacillus, Lactococcus, Bifidobacterium, Streptococcus	[73]
		Increased abundance of certain bacteria linked to inflammation and immune responses. Decreased abundance of beneficial bacteria	Increase: Clostridium, Bacteroides, Veillonella. Decrease: Lactobacillus, Bifidobacterium, Blautia coccoides/Eubacterium rectale, Prevotella	[74]
		Insulin resistance, inflammation	Decreased: Akkermansia muciniphila, Bifidobacterium	[75]
		Microbial composition influences immune responses and disease onset	Decreased: Bifidobacteria, Lachnospiracea	[76]
7	Type 2 diabetes mellitus	Changes in bile acid metabolism affecting glucose metabolism	Involvement of Clostridium, Eubacterium, Bacteroides, Lactobacillus, Bifidobacterium	[77]
		Correlation between gut microbiota composition and inflammatory markers influencing diabetes progression	Increased: Bacteroidetes, Proteobacteria. Decreased: Roseburia, Firmicutes, Clostridiaceae	[78]
		Imbalance in microbiota affecting glucose metabolism and insulin sensitivity	Decrease: Firmicutes. Increase: Bacteroidetes, Proteobacteria, Lactobacillus, Faecalibacterium prausnitzii, Blautia, Serratia	[79]
		Increased abundance of certain bacteria linked to metabolic dysfunction and inflammation	Increase: Faecalibacterium prausnitzii, Blautia. Decrease: Verrucomicrobia phylum	[80]
		Influence of SCFA production on insulin sensitivity and glucose metabolism	Increase: Bacteroides, Ruminococcus, Akkermansia muciniphila. Decrease: Roseburia, Clostridium	[81]
		Inhibit the enzyme DPP-4, which prolongs the action of incretins (e.g., GLP-1), enhancing insulin secretion and reducing glucose levels. Effects on microbiota include changes in diversity and composition	Sitagliptin and Blautia used as drug. Blautia increases, while changes in Roseburia, Clostridium, Bacteroides, Erysipelotrichaceae, and Firmicutes are variable and require more research	[82]

T2DM: Type 2 diabetes mellitus; SCFA: Short-chain fatty acid; GLP-1: Glucagon-like peptide-1; DPP-4: Dipeptidyl peptidase-4; SGLT2: Sodium-glucose cotransporter 2.