INS and preeclampsia: Metformin showed an improvement in the estimated effects of cesarean section (OR 0.82, 95% CI 0.63–1.11, Table 4), pregnancy induced hypertension (OR 0.58, 95% CI 0.34–1.12), and preeclampsia compared with insulin (OR 0.74, 95% CI 0.32–1.36); however, there is limited evidence against the hypothesis that metformin and insulin are equivalent on pregnancy outcomes.