Neuronal activity promotes glycolysis at terminals to sustain synaptic vesicle (SV) recycling; however, the underlying mechanisms are not known. Ashrafi et al. expressed a pHluorin-tagged variant of the glucose transporter GLUT4 in rat hippocampal neurons and showed that, with sustained firing of action potentials, GLUT4 is exocytosed to the cell membrane from endosomes that are distinct from SVs. Moreover, GLUT4 translocation is necessary for SV endocytosis and recycling, and relies on activation of AMP kinase. Thus, GLUT4 provides metabolic support during sustained synaptic activity.