The transporters regulating the uptake of glucose belong to the GLUT family17–19 and constitute a system of stereospecific and saturable transport/countertransport. The isoform that is predominantly expressed at the surface of adult cardiomyocytes is GLUT 4, the insulin-sensitive transporter also found in adipose tissue. 17 In addition, the cardiomyocyte expresses the GLUT 1 transporter, which is presumably independent of insulin action and predominant in fetal myocardium. 18 Both transporters have a Km for glucose (ie, the concentration of glucose at which the rate of transport is half-maximal) that is in the range of plasma glucose concentrations under fasting conditions. 20 The normal heart also expresses a low amount of GLUT 3, which has a Km below the normal plasma glucose concentration. 21 Stimulation of glucose transport is exerted by a recruitment of transporters from intracellular stores to the plasma membrane, 17–19 resulting in an increased maximal velocity of transport.