This study by Robinson et al., which included women with and without GDM (control group), concluded that in the control group, caffeine did not significantly affect blood glucose, insulin sensitivity, or C-peptide, whereas in the GDM group, C-peptide was greater (p < 0.05), and the insulin sensitivity index was lower (p < 0.05) [27,29]. The gene discussed is INS; the disease is gestational diabetes.