Glucose is a major source of ATP synthesis in platelets. As activated platelets incorporate glucose more rapidly than resting platelets, we measured the loss of glucose from extracellular media during the storage of platelet concentrates (PCs). Results showed that the loss of glucose from the extracellular media was facilitated by filter treatment or by transient formation of platelet aggregates. Further, statistically significant differences in the loss were noted among PCs prepared using different apheresis devices. Rapid loss of glucose from the extracelluar media was often accompanied by platelet shape changes in PCs examined by phase contrast microscopy but not by increased expression of P-selectin on the surface of platelets. Thus, the measurement of loss of glucose from the extracellular media may detect subtle platelet activation in PCs, contributing to our better characterization of PCs prepared with different devices or passed through different filters.