**4.4 Metformin**

Metformin, already a well-established drug for T2D, has recently been known to have bacterio-therapeutic effects on microbial composition and production of SCFA. Several recent reports have shown that metformin affects GM of T2D patients like increasing the levels of butyrate-producing bacteria. Metformin can also decrease the levels of Lactobacillus which remains high in T2D patients (**Table 2**) [125].
