As shown in Figure 2 and Table 3, significant heterogeneity was observed in the pooled analysis (I2 = 93% and PQ < 0.001); therefore, a random-effects model was used, and the pooled results indicated that CRP levels significantly decreased after metformin treatment in women with PCOS (WMD = -1.23mg/L, 95%CI: -1.65 to -0.81, P < 0.001). Here, CRP is linked to polycystic ovary syndrome.