Patients with diabetes mellitus are particularly vulnerable to cardiovascular disease. Although both the macrovascular and microvascular complications are present in patients with diabetes alone, they are particularly severe in patients with both diabetes and hypertension. While there is no doubt that a primary diabetic cardiomyopathy occurs with functional consequences, considerable evidence-both in humans and in experimental animal models-points to hypertension as of critical importance in the pathogenesis of severe pathological and symptomatic diabetic heart disease. In hypertensive-diabetic cardiomyopathy, the histopathologic myocardial damage has been attributed to hypertension, while the myocellular dysfunction has been attributed to diabetes. Together, the consequences to the myocardium are devastating. Strict control of the hypertension and diabetes mellitus, along with prevention of the microvascular consequences of both conditions, may have an ameliorative effect on the subsequent development of diabetic heart disease.