Objective:To detect the effect of insulin on apoptosis of cultured human umbilical vein endothelial cells (HUVECs) induced by hyperglycemia and the expression of caveolin-1 in HUVECs. Methods:HUVECs were cultured and randomized into group A(the controlled group,glucose concentration 5.5 mmol/L),group B (the hyperglucose group,glucose concentration 33.3 mmol/L),group C(the hyperglucose and low concentration of insulin group,glucose concentration 33.3 mmol/L+insulin concentration 20 mU/L),group D (the hyperglucose and high concentration of insulin group,glucose concentration 33.3 mmol/L+insulin concentration 1 000 mU/L). Flow cytometry was applied to determine cell apoptosis ratio and cell cycle. Cav-1 expression of HUVEC was detected by immunohistochemistry analysis. Results:High concentration of glucose induced sighificantly increased apoptosis of HUVEC which was associated with the arrest of the cell cycle of G0/G1, and the expression of cav-1 was decreased. Low concentration of insulin reduced the apoptosis of HUVEC and increased cav-1 expression. While high concentration of insulin had no effects on the cells apoptosis,cell cycle and cav-1 expression. Conclusions:Low concentration of insulin inhibited the apoptosis induced by hyperglycemia,while high concentration of insulin had no effects on the apoptosis induced by hyperglycemia, and its mechanism may be related to the expression of cav-1.