The combined results of eight studies showed that overweight women with PCOS in the metformin group did not have significantly reduced fasting insulin (WMD = 2.70, 95% CI (−15.95, 21.33), p=0.78); these studies had low heterogeneity (I2 = 56%, p=0.03) (Figure 3(c)). Here, INS is linked to polycystic ovary syndrome.