A method for calculating a bolus amount, wherein the bolus amount is calculated according to a basal rate, and a device for calculating a bolus amount according to the method, the device including an input unit used to input an amount of received carbohydrates, a computer coupled to the input unit and at least one interface used to transmit an actual blood glucose value and the value of the actual basal rate to the computer, wherein the at least one interface or another interface transmits a bolus amount calculated by the computer.