Method and software for the determination and time profile of an insulin dosis to be infused to an user. The method comprises the estimation, using an algorithm executed in a processor, of an insulin on board value, or IOB, indicative of a level of residual insulin yet active in the body of a user after being delivered to him; and the calculation, using an algorithm executed in a processor, of an insulin dosis to be delivered in successive pump instants by an insulin pump, during a given time interval, so that the estimated IOB value tracks at least one  prescribed IOB profile, independently of boluses or correction boluses previously infused to the used.