RARRES2 and gestational diabetes: When stratifying by the diagnostic criteria of GDM, patients defined by ESCPG & ACOG criteria had significantly higher chemerin levels compared with control (SMD: 6.53; 95% CI: 5.62, 7.44), but those defined by other criteria had not; although no heterogeneity was observed in the WHO subgroup (I2 = 0.0%, P = 0.490), significant heterogeneity were still found in the IADPSG subgroup (I2 = 97.6%, P < 0.001) and ADA subgroup (I2 = 99.0%, P < 0.001) (Fig. 8).