NR1H4 and type 2 diabetes mellitus: Allobaculum can produce trimethylamine oxide (Zhu et al., 2016), while trimethylamine oxide cann't only promote fat production by inhibiting BA-mediated hepatic farnesoid X receptor signal (Tan et al., 2019), but also promote IR, thereby affecting blood glucose homeostasis and the occurrence and development of T2DM (Chen et al., 2019).