Effects of type 1 diabetes mellitus on cardiac function: a study of monozygotic twins.
OBJECTIVE
To investigate left ventricular size and function in type 1 diabetes and their relation with diabetes duration, glycaemic control, autonomic dysfunction, and complications of diabetes.


METHODS
Cross sectional study using a pulsed wave Doppler echocardiogram to assess left ventricular dimensions, wall thickness, and transmitral blood flow velocity signals.


METHODS
40 monozygotic twin pairs (23 male, mean age 26 years) discordant for type 1 diabetes and 40 non-diabetic singleton controls with no clinical evidence of cardiac ischaemia.


RESULTS
For all Doppler echocardiographic measurements there were strong correlations between monozygotic twins but not between twins and control subjects. Left ventricular dimensions, wall thickness and systolic function, peak E velocity, and the velocity integrals of early left ventricular filling were similar in all three groups. Peak A velocity and the velocity integrals of late ventricular filling (mean (SD)) were greater in diabetic twins (45 (12) v 38 (8) cm/s, P = 0.002; and 32 (11) v 26 (6), P = 0.0002). Diabetic twins had lower E/A ratio (1.59 (0.39) v 1.83 (0.39), P < 0.001), greater atrial filling fraction to total diastolic filling (28 (6) v 25 (5)%, P = 0.002), and prolonged isovolumic relaxation time (72 (12) v 63 (9) ms, P < 0.001). The differences in Doppler findings between diabetic and non-diabetic twins were related to disease duration whereas the prolongation of the isovolumic relaxation time was related to cardiac autonomic dysfunction.


CONCLUSIONS
These results show that twins with type 1 diabetes have left ventricular diastolic dysfunction related to diabetes duration and cardiac autonomic dysfunction but not to glycaemic control or microvascular complications. In addition, genetic factors contribute to left ventricular dimension and function.
Lo
S S
SS
Department of Diabetes and Metabolism, St Bartholomew's Hospital, London.
Leslie
R D
RD
Sutton
M S
MS
D000293:Adolescent; D000328:Adult; D002648:Child; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003971:Diastole; D004200:Diseases in Twins; D018619:Echocardiography, Doppler, Pulsed; D005260:Female; D006801:Humans; D008297:Male; D016277:Ventricular Function, Left / Q000502:physiology*