Hypoglycaemia is known to have an effect on the electrophysiology of the heart. It can cause prolongation of the QT interval(represents the interval between the Q wave and T wave in an ECG), demonstrable with electrocardiography which may predispose some individuals to an increased risk of cardiac arrhythmias. Studies have shown this QT interval prolongation to be associated with adrenaline secretion secondary to sympathoadrenal activation during an acute episode of hypoglycaemia and this provokes a fall in plasma potassium. Electrolyte imbalances are known to predispose to arrhythmias and it is not known if other electrolyte disturbances during hypoglycaemia may also affect the QT interval.