Using the ALT level <22 U/L and BMI <25 kg/m2 as the referent group, maternal overweight/obesity at first antenatal care visit increased the adjusted OR of elevated ALT levels (≥22 U/L) for GDM risk from 1.44 (1.23 to 1.69) to 3.46 (2.79 to 4.29) with significant additive interaction (P < 0.05 for RERI, AP and S) (Tables 2 and 3). This evidence concerns the gene GPT and Obesity.