INS and polycystic ovary syndrome: The PCOS models were induced by letrozole (in seven studies), dehydroepiandrosterone (DHEA) (in six studies), estradiol valerate (in two studies), testosterone propionate (TP) (in one study), testosterone enanthate (TE) (in one study), and insulin combined with human chorionic gonadotropin (hCG) (in one study).