INS and gestational diabetes: ET-1 induced constriction in omental arteries collected from GDM patients treated with insulin was significantly reduced compared to omental arteries from diet-treated GDM patients or healthy controls; at dose 10−9 (normal vs. GDM insulin and GDM Diet vs. GDM insulin, p = 0.001), 10−8.5 (normal vs. GDM insulin and GDM Diet vs. GDM insulin, p < 0.0001), and 10−8 (normal vs. GDM insulin, p = 0.022; and GDM Diet vs. GDM insulin, p = 0.035) of ET-1 (Figure 3A).