The QT interval will be determined by the tangent or slope-intersect method. This will be an automated measurement produced by the Holter machine itself. If U waves are identified at any point, then a rhythm strip will be printed out and the QT interval determined manually by the researcher. This will be from the start of the QRS complex(represents the 'QRS complex' on the ECG which corresponds to the depolarization of the ventricles of the heart) till the nadir between the T and U wave. The QT interval will also be measured manually once (taken from the start of the QRS complex till the end of the T wave) on the baseline ECG. QTc (corrected QT interval) will be calculated using Bazett's formula which is calculated by dividing the QT interval with the square root of the RR interval. While there are a number of formulas to calculate QTc, there is no recommended standard formula for this. Bazett's formula is the most commonly used clinically. It is often criticised as it is thought to be inaccurate in extremes of heart rate, in particular tachycardia. However, since it is widely used in clinical practice to calculate QTc, and since we do not expect our subjects to exhibit extremes of bradycardia or tachycardia during the study as the blood glucose will not be allowed to fall below 2.5 mmol/L, we have chosen to use Bazett's formula.