Diverse Gut Bacteria May Ward Off Type 2 Diabetes
A diverse gut microbiome may be protective against type 2 diabetes, a new study suggested.

Previous studies have indicated that gut microbiome may be associated with development of type 2 diabetes. However, these studies are limited by small sample size and insufficient for confounding. Furthermore, which specific taxa play a role in the development of type 2 diabetes remains unclear.

This study aimed to examine associations of gut microbiome composition with insulin resistance and type 2 diabetes in a large population-based setting controlling for various sociodemographic and lifestyle factors.

This cross-sectional analysis included 2166 participants from 2 Dutch population-based prospective cohorts: the Rotterdam Study and the LifeLines-DEEP study.

The 16S ribosomal RNA method was used to measure microbiome composition in stool samples collected. The Alpha diversity (Shannon, richness, and Inverse Simpson indexes), Beta diversity (Bray-Curtis dissimilarity matrix), and taxa (from domain to genus level) were identified to reflect gut microbiome composition.

Associations among ? diversity, beta diversity, and taxa with the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and with type 2 diabetes were examined. Glucose and insulin were measured to calculate the HOMA-IR. Type 2 diabetes cases were identified based on glucose levels and medical records. Analyses were adjusted for technical covariates, lifestyle, sociodemographic, and medical factors.

Results:
-- There were 2166 participants in this study: 1418 from the Rotterdam Study (mean age, 62.4 years; 815 male) and 748 from the LifeLines-DEEP study (mean age, 44.7 years; 431 male); from this total, 193 type 2 diabetes cases were identified.

-- Lower microbiome Shannon index and richness were associated with higher HOMA-IR, and patients with type 2 diabetes had a lower richness than participants without diabetes.

-- The beta diversity (Bray-Curtis dissimilarity matrix) was associated with insulin resistance.

-- A total of 12 groups of bacteria were associated with HOMA-IR or type 2 diabetes.

-- Specifically, a higher abundance of Christensenellaceae, Christensenellaceae R7 group, Marvinbryantia, Ruminococcaceae UCG005, Ruminococcaceae UCG008, Ruminococcaceae UCG010, or Ruminococcaceae NK4A214 group was associated with lower HOMA-IR.

-- A higher abundance of Clostridiaceae 1, Peptostreptococcaceae, C sensu stricto 1, Intestinibacter, or Romboutsia was associated with less type 2 diabetes.

-- These bacteria are all known to produce butyrate.

Conclusively, in this cross-sectional study, higher microbiome alpha diversity, along with more butyrate-producing gut bacteria, was associated with less type 2 diabetes and with lower insulin resistance among individuals without diabetes. These findings could help provide insight into the etiology, pathogenesis, and treatment of type 2 diabetes.

Source: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2782527
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