(A) The viability of ARPE-19 cells treated with PBS (control), 5, 15, or 25 mM glucose for 0, 1, 2, and 3 days, respectively, was checked using the CCK-8 assay. *P < 0.05, **P < 0.01, ***P < 0.001 versus control group. (B) The relative levels of miR-218 expression in ARPE-19 cells treated with glucose were analyzed by RT-qPCR. *P < 0.05, **P < 0.01 versus control group. (C) The apoptosis of ARPE-19 cells treated with different concentrations of glucose was analyzed by flow cytometry. (D) The effect of glucose on ARPE-19 cell apoptosis was investigated by Hoechst staining (original magnification ×200, scale bar = 50 μm). All experiments were repeated three times.