Effects of acute hyperglycaemia on cardiac function: an echocardiographic study of monozygotic twins

Background: A major cause of morbidity in type I diabetes is congestive hea rt failure due predominantly to left ventricular diastolic dysfunction. The mechanism of diastolic dysfunction remains unknown and does not relate to blood pressure, microvascular complications and glycated haemoglobin. Hyper glycaemia is the hallmark of diabetes and is a potential determinant of lef t ventricular diastolic dysfunction. Objective: To determine whether acute hyperglycaemia can induce changes in left ventricular diastolic function in normal subjects similar to those observed in insulin-dependent diabetes me llitus (IDDM). Design: Cross-sectional study. Setting: London teaching hosp ital. Subjects: Sixteen twins from eight identical twin pairs discordant fo r IDDM (age 18-38 years, five male) were studied; none had a history or evi dence of myocardial ischaemia, valvular or primary heart muscle disease, sy stemic hypertension or nephropathy. Interventions: Non-diabetic twins under went a hyperglycaemic clamp at 10 mmol/l. Main outcome measures: Doppler ec hocardiography was performed in basal condition in identical twin pairs dis cordant for IDDM and repeated in the non-diabetic twins during hyperglycaem ia. Blood glucose, insulin and catecholamines were measured at baseline and during hyperglycaemia. Results: Transmitral Doppler E/A velocity ratio was significantly lower in diabetic than non-diabetic twins at baseline (1.44 (0.38) vs. 1.51 (0.19), P<0.05). Glucose infusion in the non-diabetic twins resulted in an increase in their E/A ratio (1.51 (0.19) vs. 1.82 (0.47), P <0.05) due to an increase in E velocity (68 (12) to 64.7 (10.7), P<0.05) an d a decrease in the peak A velocity (42.7 (3.85) to 38.0 (4.1), P<0.05). No significant changes were observed in peak E velocity or isovolumic relaxat ion time in the non-diabetic twins between baseline and hyperglycaemia. Con clusions:The alterations in left ventricular diastolic function induced by acute hyperglycaemia and consequent increase in plasma catecholamines do no t mimic those demonstrated in IDDM patients. (C) 2000 Elsevier Science Irel and Ltd. All rights reserved.