Objective:To observe the regulative effect of glucose and high glucose fluctuation on the proliferation,cell cycle and apoptosis in osteosarcoma MG63 cells,and study the role of non-physiological concentration of glucose in pathogenesis of diabetic osteoporosis. Methods:MG63 cells were incubated for 24 h respectively with different concentration glucose(5.5,33.3 mmol/L)and high glucose fluctuation(5.5,33.3 mmol/L). The proliferation of MG63 cells was examined by MTT colorimetric analysis. The cell cycle of the cells and apoptotic rate were determined by flow cytometry. Results:①Both high glucose and high glucose fluctuation inhibited the proliferation of MG63 cells,and the inhibition effect of high glucose fluctuation group was significantly higher than that of high glucose group(P < 0.05). ②Both high glucose and high glucose fluctuation blocked cell cycle,increased the percentage of G1 phase,decreased the percentage of S phase and induced apoptosis. The effect of high glucose fluctuation group was obviously stronger than that in high glucose(P < 0.05). Conclusion:High glucose fluctuation could not only inbihit the proliferation but also block cell cycle and induce apoptosis in MG63 cells,which may be one of the key pathogenetic factors of diabetic osteoporosis.