TGFB1 and Hyperglycemia: Cardiac fibroblasts are the main ECM-producing cells [113] and multiple pathways with a complex interplay are involved in the activation and proliferation of cardiac fibroblasts and the production of ECM proteins in diabetic cardiomyopathy, such as hyperglycemia, insulin resistance, AGEs, TGF-β, renin–angiotensin–aldosterone system (RAAS), and the imbalance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) [109].