Although the specificity of these studies largely varied (eg, location, sample size, screening methods, diagnostic thresholds), they consistently showed that as maternal BMI increased, so did the risk of being treated with insulin.12–15 32 34 36–38 Regarding the associations between smoking and GDM treatment, some studies showed that more smokers were treated with insulin than lifestyle changes,15 33 39 while others found an opposite relationship,38 40 although the differences between groups in these studies were not reported to be statistically significant. This evidence concerns the gene INS and gestational diabetes.