The existence of a diabetic cardiomyopathy has been proposed as evidence has accumulated for the presence of myocardial dysfunction in diabetic patients in the absence of ischemic, valvular or hypertensive heart disease. Diastolic dysfunction has been described as an early sign of this diabetic heart muscle disease preceding the systolic damage. Abnormalities in diastolic performance have been first demonstrated by cardiac catheterisation and subsequently by mainly using echocardiography. The pathogenesis of this left ventricular dysfunction is not clearly understood. Microangiopathy, increased extracellular collagen deposition, or abnormalities in calcium transport alone or in combination are considered to be associated with this dysfunction. The relationship between diastolic dysfunction and glycemic control is still a matter of debate. Some epidemiological and clinical arguments suggest that diastolic abnormalities may contribute to the high morbidity and mortality among diabetic patients. However, the prognostic importance of subclinical diastolic dysfunction and the possibilities for intervention are not fully known. Eventually, despite numerous studies, evidence of an intrinsic diastolic dysfunction in diabetes mellitus remains questionable. Indeed, quite contradictory results have been reported. They have been obtained in small, inhomogeneous populations, with sometimes confounding factors, using various echocardiographic indices with known limitations. Also, further studies using more refined techniques for the evaluation of diastolic function are needed, as a prerequisite, to unequivocally relate diabetes mellitus to a specific cardiomyopathy.