As the incidence of diabetes mellitus continues to rise in recent years, more and more attention has been paid to diabetic cardiomyopathy. However, the underlying molecular mechanism of cardiomyocyte dysfunction after diabetes remains unclear. The pathogenesis of diabetic cardiomyopathy is multifactorial, including impaired calcium homeostasis, up-regulated renin-angiotensin system, increased oxidative stress, altered myocardial substrate metabolism and mitochondrial dysfunction. This article reviewed how impaired energy metabolism contributes to diabetic cardiomyopathy.