In addition to the association with regulating lipid homeostasis, the nutrient regulation signal induced by an increased leucine level down-regulates the mammalian rapamycin target protein (mTOR) pathway activity and reduces insulin sensitivity by inhibiting the amino acid receptor GCN2 and AMP-activated protein kinase (AMPK) activity, which results in T2DM. The gene discussed is MTOR; the disease is type 2 diabetes mellitus.