The effect of acute hyperglycaemia on QTc duration in healthy man.
OBJECTIVE
Prolongation of heart rate-adjusted QT (QTc) is associated with an increased risk of coronary heart disease and sudden death. The objective of this study was to investigate whether acute increases of plasma glucose concentrations in healthy subjects could influence QTc and QTc dispersion.


METHODS
Plasma glucose concentrations were quickly raised to 15 mmol/l in 20 healthy subjects (10 men/10 women) and maintained for 2 h. On another occasion, and in random order, all subjects underwent the same hyperglycaemic clamp as above and an infusion of the somatostatin analogue octreotide (25 microg as iv bolus followed by a 0.5 g/min infusion) to block the release of endogenous insulin.


RESULTS
Systolic and diastolic blood pressures, heart rate and plasma catecholamine concentrations showed significant increases (p < 0.05) starting after 60 min of hyperglycaemia. QTc, QTc dispersion and PR interval also showed significant increments at 120 min of the hyperglycaemic clamp. The infusion of octreotide did not influence QTc duration, QTc dispersion, PR interval and the haemodynamic effects of acute hyperglycaemia.


CONCLUSIONS
The results show that acute hyperglycaemia produces significant increments of QTc and QTc dispersion in normal subjects. In this context, endogenously released insulin during acute hyperglycaemia seems to play a minor part.
Marfella
R
R
Department of Geriatrics and Metabolic Diseases, Second University of Naples, Itlay.
Nappo
F
F
De Angelis
L
L
Siniscalchi
M
M
Rossi
F
F
Giugliano
D
D
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D004562:Electrocardiography; D004837:Epinephrine / Q000097:blood; D005260:Female; D015309:Glucose Clamp Technique; D006339:Heart Rate; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D015282:Octreotide
D001786:Blood Glucose; D007328:Insulin; D015282:Octreotide; D009638:Norepinephrine; D004837:Epinephrine