Mothers receiving metformin had a lower incidence of maternal hypoglycemia (RR, 0.28; 95% CI, 0.10 to 0.75; P = 0.05), gestational hypertension (RR, 0.56; 95% CI, 0.36 to 0.87; P < 0.01), and induction of labor (RR, 0.85; 95% CI, 0.74 to 0.99; P < 0.05) than those in the insulin group. This evidence concerns the gene INS and Hypoglycemia.