Cardiovascular disease is the most common cause of death in patients with diabetes mellitus (DM). In particular, the focus of many studies has been on ischemic heart disease, as it is a eading cause of death in diabetic patients. However, independent of coronary artery disease, DM can also lead to cardiac structural and functional changes, supporting the presence of diabetic cardiomyopathy. The pathologic mechanismin the development of diabetic cardiomyopathy is multifactorial including metabolic disturbance, myocardial fibrosis, microvascular disease, and autonomic dysfunction. Functionally, diabetic patients have a higher prevalence of LV (left ventricle) diastolic dysfunction. Because most diabetic patients with early myocardial disease have a wide spectrum of diastolic dysfunction at rest, assessment of LV functional reserve during exercise is helpful for early identification of myocardial dysfunction. Recent research has demonstrated that LV diastolic functional reserve (DFR) assessed by diastolic stress echocardiography was significantly reduced in patients with DM, compared with a control group, suggesting DFR might be an early indicator of diabetic cardiomyopathy. Glycemic control might be the most important and basic therapeutic strategy for preventing the development of diabetic cardiomyopathy. However, more extensive studies are needed to garner further evidence of preventive and therapeutic strategies of diabetic cardiomyopathy.