Fig. 1Schematic depiction of impact “on” and impact “of” myocardial glucose metabolism during the initiation and progression of cardiomyopathy. During diabetes overall glucose utilization is blunted (down arrows) at the level of glucose uptake, glycolysis, and glucose oxidation. Partially through regulation of the glucose transporters (GLUT1 and 4) although other cardiac expressed family members may play a role (GLUT8, 3, 10, 11, and 12). Fatty acids are known to have negative effect on glucose transport via myocardial insulin resistance and on glucose oxidation by inhibiting the pyruvate dehydrogenase (PDH) complex activity. Non-oxidative pathways (up arrows) of glucose metabolism such as polyol pathway, advanced glycation end product (AGE) pathway, and protein kinase C pathway to produce excess reactive oxygen species (ROS) leading to oxidative stress. Induction of O-linked N-acetylglucosamine (O-GlcNAc) modification of via increased hexosamine biosynthesis flux disrupts cardiac protein contractility, calcium sensitivity, calcium cycling, and mitochondrial function. Also, modification of nuclear transcription factors (TFs) and histones (e.g., H3) may contribute to gene expression changes in diabetic cardiomyopathy. Brown arrows indicate glucose metabolite flux and its regulation by diabetes. Black arrows illustrate fatty acid-mediated pathways altering glucose utilization. Blue arrows indicate pathways induced by non-adenosine triphosphate (ATP) producing pathways of glucose metabolism owing to reduced glycolysis and glucose oxidation. PFK, phosphofructokinase; STIM1, stromal interaction molecule 1; SERCA2a, sarco/endoplasmic reticulum Ca2+ ATPase; PDK, pyruvate dehydrogenase kinase; FA, fatty acids.