For offspring type 2 diabetes, GDM without insulin during pregnancy was significantly associated with increased risk (HR, 1.281 [1.146-1.433]), with a greater risk among insulin-treated GDM pregnancies (HR, 4.329 [3.555-5.270]).<h4>Conclusions</h4>Maternal GDM without insulin therapy is associated with an increased risk of type 2 diabetes, but not type 1 diabetes, in offspring, whereas insulin treatment for GDM during pregnancy is associated with increased risk for both type 1 and type 2 diabetes. This evidence concerns the gene INS and type 1 diabetes mellitus.