A method and apparatus for determining hyperglycaemia. The apparatus includes a sensor and a processor, to determine a QT interval of a patient and any rate of change of the QT interval (dQT/dt), and, output means, to provide an output signal indicative of hyperglycaemia using an algorithm based on the combination of the QT interval and the rate of change of the QT interval. The apparatus may further include further sensor means, to determine a TpTec parameter and the SDNN parameter of a patient, whereby the processor further determines any rate of change of the TpTec parameter (dTpTec/dt) and the SDNN parameter to provide an output signal based on any one or combination of the QT interval, the TpTec parameter, the SDNN parameter and the rate of change of these parameters.
