O-linked N-acetylglucosamine (O-GlcNAc) is attached to and detached from proteins by O-GlcNAc transferase (OGT) and O-GlcNAcase, respectively. It has been proposed that streptozotocin induces pancreatic beta -cell death by blocking O-GlcNAcase and increasing O-GlcNAc. To elucidate the relationship between cytosolic O-GlcNAc accumulation and beta -cell death, we treated beta -cell lines HIT-T15 and Min6 with glucosamine. Glucosamine markedly reduced cell viability in both cell lines only at 10 mM. The measurement of cytosolic O-GlcNAc under glucosamine treatment revealed that O-GlcNAc accumulation was observed even at 2 mM glucosamine and maximized at 5 mM, but did not occur very well at 10 mM. Furthermore, 100 muM PUGNAc, an inhibitor of O-GlcNAcase, increased cytosolic O-GlcNAc but did not induce cell death in these cells. Therefore, no correlation between accumulation of cytosolic O-GlcNAc and beta -cell death was suggested. Alternatively, inosine partially rescued cell death induced by glucosamine in Min6 cells, suggesting that energy depletion partly contributes to,beta -cell death by glucosamine.