DNMT3B and type 2 diabetes mellitus: Further analysis using pancreatic islets from T2DM and non-T2DM human donors was conducted to determine the mRNA expression levels of MECP2, DNMT1, DNMT3A, and DNMT3B, along with the DNA methylation status of 12 CpG sites (five upstream and seven downstream) associated with the GLP-1R TSS.