Abstract: Objective To study the impact of high concentration insulin on the proliferation and apoptosis of K562 cell strain. Methods K562 cells were treated with different concentrations of insulin. The proliferation activity was tested by CCK-8 assay, cytometry, and trypan blue exclusion. The alterations in glucose concentration of the culture media were monitored while the apoptosis of K562 cells was detected by flow cytometry. The effects of high concentration insulin on the proliferation of K562 cells were inhibited by varying concentrations of insulin-like growth factor-1 (IGF-1) and Suramin. Results Under the range of concentration (0.1-1 mU/mL), insulin facilitated the proliferation of K562 cells. In contrast, insulin at high concentrations (1.6-100 mU/mL) had the opposite effect, in a dose- and time-dependent manner. Different concentrations of glucose in the culture medium had no significant influence on the inhibitory effect of high concentration insulin on the proliferation of human leukemia cell strain K562. At low concentration insulin inhibited the apoptosis of K562 cells, in a dose-dependent manner. In contrast, insulin at high concentration had the opposite effect, in a dose-dependent manner. Furthermore, IGF-1 reversed the inhibitory effect of high concentration insulin on the proliferation of K562 cell in a dose- and time-dependent manner. Suramin, which is an IGF-1 receptor non-specific blocker, had the opposite effect on K562 cells, also in a dose- and time-dependent manner. Conclusion These results indicate insulin has a dual effect on K562 cells. The dual effect is probably mediated by the binding of insulin and IGF-1R. Inhibitory effect of high concentration insulin on the proliferation of K562 cells is unrelated with the glucose metabolism in the culture media.