As testosterone and oestrogen levels are both altered in the LET mouse model and women with PCOS may have altered aromatase activity, we used DHT and ovariectomy (OVX) models to explore the contributions of hyperandrogenism and oestrogen deficiency both independently and in combination to the development of insulin resistance and gut dysbiosis in pubertal female mice. This evidence concerns the gene CYP19A1 and polycystic ovary syndrome.