The causal relationship between gut microbiota and type 2 diabetes: a two-sample Mendelian randomized study.

Area of Science:

• Microbiome research
• Metabolic disease genetics
• Human health and disease

Background:

• Type 2 diabetes mellitus (T2DM) is a global metabolic disease with no cure.
• Gut microbiota composition is increasingly linked to metabolic disease, but its direct role in T2DM remains unclear.

Purpose of the Study:

• To investigate the causal relationship between gut microbiota and T2DM using Mendelian randomization.
• To identify specific gut bacteria that influence T2DM risk or protection.

Main Methods:

• Utilized summary statistics from the MiBioGen consortium (microbiota) and GWAS database (T2DM).
• Employed a two-sample Mendelian randomization (MR) approach, primarily using Inverse Variance Weighted (IVW) methods.
• Assessed heterogeneity and horizontal pleiotropy using Cochran's Q and MR-Egger tests.

Main Results:

• Initially identified protective genera (e.g., *Flavonifractor*, *Haemophilus*) and risk families/genera (e.g., *Clostridiaceae1*, *Actinomyces*) for T2DM.
• After False Discovery Rate correction, *Flavonifractor*, *Haemophilus*, *Clostridiaceae1*, *Actinomyces*, and *Candidatus Soleaferrea* showed significant causal effects.
• No significant heterogeneity or horizontal pleiotropy was detected.

Conclusions:

• Confirmed causal links between specific gut bacteria (*Flavonifractor*, *Haemophilus*, *Clostridiaceae1*, *Actinomyces*, *Candidatus Soleaferrea*) and T2DM.
• Findings offer potential new strategies for T2DM treatment and early screening.
• Further research is essential to elucidate the protective and detrimental mechanisms of these bacteria in T2DM.