The invention relates to a method for supplying current to a glow plug in a running diesel engine after reaching the operating temperature thereof by a series of current pulses, wherein a piston of the engine carries out a work cycle comprising several strokes and the glow plug is supplied with current as a function of the strokes of the work cycle such that the electric current supplied in each work cycle is mainly supplied at a predetermined, steady stroke of the piston, wherein control time intervals that follow each other are defined, during which up to two switching processes can be triggered by a control device, by which the glow plug can be connected to a voltage source for creating a current pulse or can be disconnected from the voltage source for ending a current pulse. According to the invention, the control time intervals have a duration that can be varied by the control device as a function of the rotational speed of the engine.