Objectives Diabetic patients continued to develop vascular complications despite achieving normal glucose level, suggesting metabolic memory which was associated with histone H3 lysine (H3K9) methylation through gene repression.Here we hypothesised that H3K9 di-methylation (H3K9me2) might be involved in vascular remodelling under diabetic condition;and histone demethylase KDM3A, an important regulator for H3K9me2,might play a key role in these pathologies.