INS and polycystic ovary syndrome: As presented in Table 4, the combined use of metformin and simvastatin are more beneficial to reduce the FIN level (SMD –1.17, 95% CI –2.09 to –0.26) than metformin alone treatment in PCOS patients (P = .014), and there was no significant difference in the FBS (SMD 0.23, 95% CI –0.52–0.97) and insulin sensitivity index (SMD –0.17, 95% CI –0.48–0.15) between experimental and control groups (all P > .05).