Interrelationship of Gut Microbiota, Obesity, Body Composition and Insulin Resistance in Asians with Type 2 Diabetes Mellitus

Metabolic syndrome (MS) has been an important health issue in the world, and insulin resistance (IR) is one of the characteristics of MS, increasing the risk for the onset and poor prognosis of type 2 diabetes mellitus (T2D). However, the interactional effect of obesity or abnormal body composition on the correlation between gut microbiota and IR in T2D patients is not well-explored. This cross-sectional study used a body composition monitor to evaluate lean tissue mass and fat tissue mass. IR was calculated using homeostatic model assessment-insulin resistance (HOMA-IR). Eight pairs of 16S rRNA gene primers specific to Firmicutes, Bacteroidetes, Clostridium leptum group, Faecalibacterium prausnitzii, B acteroides, Bifidobacterium, Akkermansia muciniphila, and Escherichia coli were utilized to measure their abundance by qPCR. One hundred and fifty-four T2D patients were enrolled and stratified by the median HOMA-IR (2.5) and body mass index (BMI) of 25 kg/m(2). A lower abundance of A. muciniphila was found in T2D patients with high HOMA-IR and BMI respectively. HOMA-IR and BMI had a synergistic effect on the reduction of the abundance of A. muciniphila. After adjusting metabolic factors, the low abundance of A. muciniphila significantly increased the risk for greater severity of IR. Furthermore, the negative correlation between A. muciniphila and IR was only found in T2D patients with high lean tissue. In conclusion, decreased abundance of fecal A. muciniphila enhanced the severity of IR in Asians with T2D, especially those having lean mass, and this significant relationship was independent of obesity.