Acute activation of the serine-threonine kinase, Akt is cardioprotective and increases glucose uptake at least in part through enhanced expression of the GLUT4 glucose transporter on the sarcolemma. The effects of chronic Akt activation on glucose uptake in the heart remain unclear. To address this issue, we examined the effects of chronic Akt activation on glucose uptake, glycogen storage, and relevant glucose transporters in the hearts of transgenic mice. We found that chronic cardiac activation of Akt led to a substantial increase in the rate of basal glucose uptake (p<0.05) but blunted the response to insulin (1.9- vs 18.1-fold increase compared to baseline) using NMR in ex vivo perfused heart. Basal glucose uptake was also increased in Akt transgenic mice in vivo (p<0.005). These changes were associated with an increase on glycogen deposition, examined with histochemical staining, biochemical (>6-fold, p<0.001) and in vivo radioactive (5-fold, p<0.01) assays. Studies in chimeric hearts of female X-linked transgenic Akt mice suggested that increased glycogen deposition occurred as a cell autonomous effect of transgene expression. Interestingly, while sarcolemmal GLUT1 was not significantly altered, chronic Akt activation actually decreased plasma membrane GLUT4. Moreover, intracellular pools of GLUT1 were modestly reduced while intracellular GLUT4 was substantially reduced. It seems likely that neither GLUT1 nor GLUT4 explain the increase in basal glucose uptake but that these reductions contribute to the loss of insulin responsiveness that we observed. These data demonstrate that chronic Akt activation increases basal glucose uptake and glycogen deposition while inhibiting the response to insulin.