As a causal factor of GLUT reduction, it has been implicated that over-activation of hexosamine pathway by hyperglycemia decreases the expression level of GLUT2 in the pancreatic β-cells, eventually leading to the inhibition of glucose-stimulated insulin secretion and induction of apoptosis in β-cells (Yoshikawa et al., 2002). The gene discussed is SLC2A1; the disease is Hyperglycemia.