INS and polycystic ovary syndrome: Since high levels of circulating insulin stimulating the ovarian theca cells to produce androgen had been supported by various experiments, both in vitro and in vivo (Poretsky, 1991), a new microbiological hypothesis for the development of PCOS suggested that dysbiosis of gut microbiota can increase the ovaries production of androgens, and then interfere with normal follicle development via triggering a chronic inflammatory response and insulin resistance (Tremellen and Pearce, 2012).