In this report we demonstrate that, in pancreatic β-cells, eIF2α phosphorylation in response to a decrease in glucose concentration is primarily mediated by the activation of PKR-like ER kinase (PERK). We provide evidence that this increase in PERK activity is evoked by a decrease in the energy status of the cell via a potentially novel mechanism that is independent of IRE1 activation and the accumulation of unfolded nascent proteins within the ER. The inhibition of eIF2α phosphorylation in glucose deprived cells by the over-expression of dominant-negative PERK or an N-terminal truncation mutant of GADD34 leads to a 53% increase in the rate of total protein synthesis. Polysome analysis revealed that this coincides with an increase in the amplitude but not the number of ribosomes per mRNA, indicating that eIF2α dephosphorylation mobilises hitherto untranslated mRNAs onto polysomes. In summary, we show that PERK is activated at low glucose in response to a decrease in energy status and that this plays an important role in glucose regulated protein synthesis in pancreatic β-cells.