Objective To investigate the effect of microRNA-182-5p (miR-182-5p) on high glucose-induced endothelial injury.Methods Human umbilical vein endothelial cells (HUVECs) were cultured and randomly divided into the control group, high glucose plus mimic control group, high glucose plus mimic group, high glucose plus inhibitor control group and high glucose plus inhibitor group. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx), caspse-3 and lactate dehydrogenase (LDH), the levels of 3nitrotyrosine (3-NT) and malondialdehyde (MDA) were measure by the commercial kits. Quantitative real-time PCR and immunoblots were used to detect the mRNAor protein levels. CCK-8 method was performed to measure cell viability, while 2′, 7′-dichlorofluorescin diacetate (DCFH-DA) staining was done to evaluate reactive oxygen species (ROS) level. TargetScan software prediction and the luciferase reporter gene assay were used to verify the direct modulation of miR-182-5p on the 3′untranslational region (UTR) of SIRT1. Results Compared with the control group, endothelial cells with high glucose treatment had elevated miR-182-5p expression. The incubation of miR-182-5p mimic exacerbated, whereas miR-182-5p inhibitor alleviated high glucose-induced oxidative stress and cell death. Endothelial SIRT1 expression was decreased by miR-182-5p mimic, while increased by the inhibitor upon high glucose stimulation. Furthermore, the protective effects of miR-182-5p inhibitor were abolished in cells with small interfering RNA against SIRT1 transfection. miR-182-5p directly bound to the 3′-UTR of SIRT1 and caused its downregulation.Conclusion miR-182-5p decreases endothelial SIRT1 expression, thereby aggravating oxidative stress and cell death upon high glucose stimulation. Inhibition of miR-182-5p produces significant benefits to endothelial cells.