A device for determining blood glucose characteristics, comprising: - a sensor input capable of receiving a signal from a sensor, the signal being based on a sensed blood glucose value of a user, - a memory, configured for storing a plurality of measurements of the sensed blood glucose value of the user from the received signal from the sensor, - a display, configured for presenting a graphical representation of the plurality of measurements of the blood glucose characteristic value, and - a controller, configured for controlling the presentation of the graphical representation on the display, wherein the controller is further configured to perform a time analysis for determining a measurement time for an early measurement providing a first sensed blood glucose value assigned to a first range of sensed blood glucose values and a later measurement providing a second sensed blood glucose value assigned to a second range of sensed blood glucose values, wherein the graphical representation comprises a trend indicator indicating an approximate value trend in the sensed blood glucose value over a recent series of the plurality of measurements, wherein the trend indicator comprises a plurality of graphical segments (23, 24), each of the graphical segments (23, 24) being of different graphical style and assigned to a different range of sensed blood glucose values, thereby indicating a transition from the first range of sensed blood glucose values to the second range of sensed blood glucose values, and characterized in that the controller is further configured to - prevent the graphical representation of the trend indicator on the display if from the time analysis one of the following conditions is concluded: - a time interval between the early and the later measurement is shorter than a minimum time interval, and - the time interval between the early and the later measurement is longer than a maximum time interval. - a sensor input capable of receiving a signal from a sensor, the signal being based on a sensed blood glucose value of a user, - a memory, configured for storing a plurality of measurements of the sensed blood glucose value of the user from the received signal from the sensor, - a display, configured for presenting a graphical representation of the plurality of measurements of the blood glucose characteristic value, and - a controller, configured for controlling the presentation of the graphical representation on the display, wherein the controller is further configured to perform a time analysis for determining a measurement time for an early measurement providing a first sensed blood glucose value assigned to a first range of sensed blood glucose values and a later measurement providing a second sensed blood glucose value assigned to a second range of sensed blood glucose values, - prevent the graphical representation of the trend indicator on the display if from the time analysis one of the following conditions is concluded: - a time interval between the early and the later measurement is shorter than a minimum time interval, and - the time interval between the early and the later measurement is longer than a maximum time interval. - a time interval between the early and the later measurement is shorter than a minimum time interval, and - the time interval between the early and the later measurement is longer than a maximum time interval.