Background/Aims: To investigate the effects of miR-137 on high glucose (HG)-induced vascular injury, and to establish the mechanism underlying these effects. Methods: Human umbilical vein endothelial cells (HUVECs) were transfected with miR-137 inhibitor or mimic, and then treated with normal or high glucose. Cell viability and apoptosis were detected by using the Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. Reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) were detected by fluorescent probe (DCFH-DA), thiobarbituric acid reaction, and the nitroblue tetrazolium assay, respectively. The mRNA and protein expressions of AMPKa1 were determined by qRT-PCR and Western blotting. Results: Down-regulation of miR-137 dramatically reverted HG-induced decreases in cell viability and SOD levels and increases in apoptosis, ROS and MDA levels. Moreover, bioinformatics analysis predicted that the AMPKa1 was a potential target gene of miR-137. Luciferase reporter assay demonstrated that miR-137 could directly target AMPKa1. AMPKa1 overexpression had the similar effect as miR-137 inhibition. Down-regulation of AMPKa1 in HUVECs transfected with miR-137 inhibitor partially reversed the protective effect of miR-137 inhibition on HG-induced oxidative stress in HUVECs. Conclusion: Down-regulation of miR-137 ameliorates HG-induced injury in HUVECs by overexpression of AMPKa1, leading to increasing cellular reductive reactions and decreasing oxidative stress. These results provide further evidence for protective effect of miR-137 inhibition on HG-induced vascular injury. (C) 2016 The Author(s) Published by S. Karger AG, Basel