Progressive loss of β-cell identity and insulin resistance is generally associated with type 2 diabetes.331 It has been observed that downregulation of CBP/p300-mediated H3K27 deacetylation promoted β cell failure in type 2 diabetes in islets of prediabetic db/db mice.332 Moreover, in hyperglycemia, loss of p300 histone acetyl transferase activity promotes β cell apoptosis.333 However, unbalanced levels of histone acetylation have been found to be involved with diabetic retinopathy, one of the major causes of diabetes-associated morbidity. This evidence concerns the gene EP300 and diabetes mellitus.