PDK4 and Hyperglycemia: Chronic hyperglycemia is primarily elicited by insulin deficiency and/or resistance and damages the myocardium by reducing the expression of glucose transporters, by increasing the expression of the pyruvate decarboxylase inhibitor pyruvate dehydrogenase kinase-4 (PDK4), and by raising the flux of glucose into hexosamine, pentose and polyol pathways.