This study aimed to screen microRNAs and their corresponding target genes that are associated with vascular injury in type two diabetes mellitus (T2DM), investigate the effects of differentially expressed miRNAs and their target genes on high glucose-induced vascular injury and establish the mechanism underlying these effects. A high-throughput digital gene expression (DGE) sequencing was performed to sequence microRNAs (miRNAs) and messenger RNAs (mRNAs) and determine their differential expression in human umbilical vein endothelial cells (HUVECs) incubated with serum samples from patients with T2DM and healthy volunteers. The HUVECs were transfected with si-TNF-α (tumor necrosis factor α) and a miR-149-5p inhibitor or mimic in vitro and then treated with normal or high glucose. The relative content of nitric oxide (NO) in the cells was detected using the Griess Reagent System. The mRNA and protein expression of endothelial nitric oxide synthase (eNOS) were determined by qRT-PCR and Western blotting. The content of endothelin-1 (ET-1), von Willebrand factor (vWF), and intercellular adhesion molecular-1 (ICAM-1) were detected using an enzyme-linked immunosorbent assay (ELISA) kit. Apoptosis was determined by flow cytometry using the Annexin V/PI apoptosis detection kit. The mRNA and protein expression levels of ER stress (ERS) markers were determined by qRT-PCR and Western blotting. Based on the high-energy sequencing and in vitro pre-experiment studies, we determined that miR-149-5p and TNF-α were a differentially expressed mRNA/miRNA pair in T2DM with vascular injury. The luciferase reporter assay results demonstrated that miR-149-5p could directly target TNF-α. The upregulation of miR-149-5p reduced the high glucose-induced dysfunction in the HUVECs by significantly decreasing the levels of ET-1, vWF, and ICAM-1 and increasing the level of NO and the expression of eNOS. Additionally, we found that miR-149-5p can improve cell injury and reduce apoptosis by restoring the ameliorated high glucose-induced expression of ERS markers. TNF-α and miR-149-5p were differentially expressed in T2DM vascular endothelial injury. The over-expression of miR-149-5p ameliorates the high glucose-induced injury in the HUVECs by regulating the expression of TNF-α and ERS markers. © 2017 The Author(s). Published by S. Karger AG, Basel.