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The development of a diabetic cardiomyopathy is a multifactorial process, and evidence is accumulating that defects in intracellular free calcium concentration [Ca2+]i or its homeostasis are related to impaired mechanical performance of the diabetic heart leading to a reduction in contractile dysfunction. Defects in ryanodine receptor, reduced activity of the sarcoplasmic reticulum calcium pump (SERCA) and, along with reduced activity of the sodium-calcium exchanger (NCX) and alterations in myofilament, collectively cause a calcium imbalance within the diabetic cardiomyocytes. This in turn is characterized by cytosolic calcium overloading or elevated diastolic calcium leading to heart failure. Numerous studies have been performed to identify the cellular, subcellular, and molecular derangements in diabetes-induced cardiomyopathy (DCM), but the precise mechanism(s) is still unknown. This review focuses on the mechanism behind DCM, the onset of contractile dysfunction, and the associated changes with special emphasis on hyperglycemia, mitochondrial dysfunction in the diabetic heart. Further, management strategies, including treatment and emerging therapeutic modalities, are discussed. [ABSTRACT FROM AUTHOR]

Heart failure in chronic type 2 diabetes mellitus is partly attributable to adverse structural remodelling of the left ventricle (LV), but the contribution of hyperglycaemia (HG) per se in remodelling processes is debated. In this study, we examined the molecular signature of LV remodelling in 18-month-old spontaneously diabetic male Goto-Kakizaki (GK) rats that represent a long-term mildly diabetic phenotype, using histological, immunoblotting and quantitative gene expression approaches. Relative to age-matched Wistar controls, mildly diabetic GK rats presented with LV hypertrophy, increased expression of natriuretic peptides and phosphorylation of pro-hypertrophic Akt. Fibrosis proliferation in the GK LV paralleled increased transcriptional and biologically active pro-fibrogenic transforming growth factor-β1 (TGFβ1) in the LV with upregulated mRNA abundance for key extracellular matrix (ECM) components such as fibronectin, collagen type(s) 1 and 3α and regulators including matrix metalloproteinases 2 and 9, and their tissue inhibitor (TIMP) 4, connexin 43 and α5-integrin. GK rats also presented with altered mRNA expression for cardiac sarcoplasmic reticulum CaATPase, Na/Ca exchanger and the L-type Ca channels which may contribute to the altered Ca transient kinetics previously observed in this model at 18 months of age ( t test, p < 0.05 vs. age-matched Wistar control for all parameters). The results indicate that chronic mild HG can produce the molecular and structural correlates of a hypertrophic myopathy. Diffuse ECM proliferation in this model is possibly a product of HG-induced TGFβ1 upregulation and altered transcriptional profile of the ECM. [ABSTRACT FROM AUTHOR]