Exercise-induced left ventricular dysfunction in young men with asymptomatic diabetes mellitus (diabetic cardiomyopathy)

Radionuclide ventriculographic studies were performed at rest and during exercise on 30 consecutive men, aged 21 to 35 years with diabetes mellitus without evidence of coronary artery or any other cardiovascular disease, and in 20 normal age-matched subjects. Sixteen (53%) were treated with insulin and 14 (47%) were treated with either diet (6 patients) or oral antidiabetic therapy (8 patients). All patients from both groups had normal left ventricular (LV) ejection fraction (EF) at rest. In 5 of the 30 diabetic patients (17%), LVEF decreased after exercise, in 8 (27%) it remained unchanged and in 17 it increased normally. Mean LVEF at rest and after exercise in this group was 66 +/- 7% and 72 +/- 7% (+/- standard deviation), respectively. In all normal subjects, LVEF increased after exercise. Mean LVEF at rest and after exercise in the normal group was 66 +/- 7% and 76 +/- 9%, respectively. No patient had evidence of regional dysfunction at rest or after exercise. LV function was not related to serum glucose levels during the test, modality of treatment, insulin dependency or duration of the disease. Three of 4 patients with diabetic microvascular complications showed LV dysfunction. In 4 of 5 patients in whom LVEF decreased after exercise, thallium studies showed normal perfusion. Thus, diabetes mellitus may cause exercise-induced global LV dysfunction in young men with no evidence of cardiovascular disease. This phenomenon apparently does not seem to follow the known course of diabetic microvascular complications.