Heart failure is prevalent in diabetic patients. The diabetic cardiomyopathy is defined as the abnormalities in myocardial structure and function that occur independently of well-known cardiovascular risk factors in diabetes mellitus. Diabetes mellitus is associated with typical alterations in myocardial substrate metabolism and energetics that may play a role in diabetic cardiomyopathy. Molecular imaging with positron emission tomography (PET) using tracers of glucose, fatty acid and oxidative metabolism has contributed to understanding myocardial metabolic abnormalities associated with diabetes mellitus as well as effects of pharmaceutical interventions on these abnormalities. Other molecular imaging PET tracers may be used to characterize various myocardial alterations potentially associated with diabetes, such as myocardial autonomic neuronal function, inflammation and fibrosis. This review aims at summarizing the PET imaging tools that can be potentially used to study various aspects of diabetic cardiomyopathy.