In order to clarify the preclinical abnormalities of the cardiac function in subjects with diabetes mellitus without heart failure, we studied the cardiovascular responses to continuous iv infusion of epinephrine.
Subjects: Fourteen diabetic and 6 non-diabetic non-obese individuals (ages 38-60) without any cardiovascular abnormalities such as heart failure, hypertension and electrocardiographic abnormalities were investigated.
Method: Epineprhine was administered by continuous iv infusion at the rate of 1.5 and 3.0 μg/h/kg for 20 min. The cardiovascular response to epinephrine infusion was assessed by using the M-mode echocardiography and continuous blood pressure and pulse rate monitoring system. Increase in the ejection fraction (EF) following the epinephrine infusion above the basal EF was assessed from the echocardiogram by using Teichholtz's equation. The following results were obtained.
Plasma epinephrine levels in the diabetic and non-diabetic subjects were similar. There was no significant difference in basal EF between diabetic and non-diabetic subjects.ΔEF was significantly negatively correlated with the duration of diabetes (r=-0.70, p<0.005), but not with age of the diabetic subjects (r=-0.05, NS).ΔEF in diabetic subjects with a complication was less than that in non-diabetics (p<0.005). In particular ΔEF in diabetics with autonomic neuropathy was further blunted, even though the tachycardic response to the epinephrine infusion in those subjects was significantly accentuated. There was a significant negative correlation (r=-0.86, p<0.005) between ΔEF and the HbA₁ levels in diabetic subjects without severe complications.
These results indicate that the response of cardiac function to epinephrine infusion in diabetic subjects without any clinical cardiovascular abnormalities is defective. This defective cardiac response is correlated with either the duration of diabetes, severity of the diabetic complication or glycemic control.