Gut microbial dysbiosis index in relation to type 2 diabetes mellitus and glycometabolic abnormalities: The potential mediating role of triglyceride-glucose body mass index

Background: The Microbial Dysbiosis Index (MDI) quantifies gut microbiota imbalance, but its association with Type 2 Diabetes Mellitus (T2DM) and glycometabolic abnormalities remains unclear. The Triglyceride-Glucose Body Mass Index (TyG-BMI) is a surrogate marker of insulin resistance.

Objective: This study aimed to investigate the associations of MDI with T2DM and glycometabolic abnormalities and to explore whether TyG-BMI mediates these associations.

Methods: The data of this case-control study came from the Henan rural cohort in China. Gut microbiota profiles were characterized using 16S rRNA gene sequencing, and MDI was constructed to quantify gut microbial dysbiosis. Logistic regression and generalized linear models were used to examine the associations of gut microbial alpha diversity, genus-level taxa, MDI, and TyG-BMI with T2DM and glycometabolic indicators. Mediation analyses were performed to evaluate whether TyG-BMI mediated the associations of MDI with T2DM and related glycometabolic indicators.

Results: Lower gut microbial alpha diversity was associated with higher Fasting Plasma Glucose (FPG) and Glycated Hemoglobin A1c (HbA1c) levels and lower Homeostasis Model Assessment of -cell function (HOMA2-%). Genus-level analysis identified 30 bacterial genera associated with glycometabolic indicators, including six genera that were also associated with TyG-BMI. Higher MDI was associated with increased odds of T2DM, higher FPG andHbA1c levels, and lower HOMA2-%. TyG-BMI partially mediated the associations of MDI with T2DM, FPG, and HbA1c, with mediation proportions of 19.56%, 18.36%, and 16.07%, respectively.

Conclusions: Gut microbial dysbiosis is associated with T2DM-related glycometabolic abnormalities. The partial mediation by TyG-BMI suggests a potential metabolic link between gut microbiome imbalance and impaired glucose metabolism, providing new insight into the gut microbiomemetabolism axis in T2DM.

Keywords: Microbial Dysbiosis Index, Gut Microbiome, Type 2 Diabetes Mellitus, Triglyceride-Glucose Body Mass Index, Glycometabolic Abnormalities.

Biwen Shi is a master’s student at Zhengzhou University, China. Her research focuses on microbiology and chronic metabolic diseases, with a special interest in Type 2 Diabetes Mellitus (T2DM). She is familiar with data analysis and participates in the Henan prospective cohort study of the research group.