A method and device for warning diabetics of imminent hypoglycaemic attacks. EEG signals are collected from a person using subcutaneously placed electrodes and the signals are led via wires drawn under the persons skin to a subcutaneously placed signal interface unit from where they are transmitted to an externally worn signal processing unit. The signal processing analyzes the EEG signals and when the pre-seizure characteristics signal changes are detected, a warning signal is given to the person from an alarm giver built into the signal processing unit, e.g., in form of a vibrator. When a person detects a warning signal, the person can prevent the hypoglycaemic attack by, e.g., consuming a sugary food.
