Diabetes mellitus (DM) poses a persistent challenge in managing cardiovascular (CV) complications, despite advancements in treatment. The glycemic control alone fails to reduce CV complications, revealing that glucose exerts adverse effects even after achieving normal blood levels, phenomenon known as glycemic memory. Our studies on endothelial cells from umbilical cords of gestational diabetic women (GD-HUVEC) suggest a persistent proinflammatory state possibly regulated by epigenetic changes. Recent studies highlight the key role of epigenetic changes and regulators in DM-related complications, like histone 3 acetylation at the 27 lysine residue (H3K27ac) catalysed by the acetyltransferase p300 and the enhancer regulator BRD4, binding to H3K27ac. NEO2734, an inhibitor targeting p300 and BRD4, has shown promise in preclinical cancer studies and holds potential as a dual-target therapy for DM. Thus, we investigated whether NEO2734 can address epigenetic dysregulation linked to endothelial dysfunction in DM. In our study using GD-HUVEC as a model, we observed elevated gene expression of the pro-inflammatory factor NF-kBp65 compared to controls (Real-time qPCR). Moreover, luciferase assay and ChIP analysis revealed an increase in histone 3 methylation at the 4 lysine (H3K4me1) and H3K27ac at a putative enhancer site of NF-KBp65 in GD-HUVEC compared to controls. Interestingly, both GD-HUVEC and control cells exposed to high glucose showed significantly higher BRD4 protein expression compared to control cells via flow-cytometry. Therefore, through MTT assay, we tested NEO2734 toxicity on HUVEC observing a significant reduction of NF-KB p65 protein expression in GD-HUVEC at a very low concentration (0.001 μM). In conclusion, these findings contribute to our understanding of epigenetic regulation in DM and establish NEO2734 as a promising candidate for addressing CV complications.