INS and gestational diabetes: A confounder adjusted large meta-analysis based on 156 observational studies of GDM vs NGT controls (including 35 studies of women with diet-treated GDM) reported increased odds of cesarean section (1.16; 1.03-1.32) in women with diet-treated GDM, whereas 63 studies comparing insulin-treated women with GDM with healthy controls found no differences in maternal outcomes.