TGFB1 and Myocardial fibrosis: However, miR-15a/b expression is downregulated and TGF-β and connective tissue growth factor (CTGF) expression is upregulated in diabetic hearts characterized by progressive myocardial fibrosis, mouse models, and high-glucose-induced cardiomyocytes, which can be reversed by restoring miR-15a/b expression, as it reduces the differentiation of cardiac fibroblasts and improves myocardial fibrosis [51].