PIK3CA and gestational diabetes: In addition, the expression and phosphorylation of insulin signaling downstream regulators in GDM change in terms of insulin receptor substrate-1 (IRS1), insulin receptor substrate 2 (IRS2), Phosphatidylinositol-3-kinase subunit p85 (PIK3R1), and Phosphoinositol-3-kinase-α (PIK3CA).