A monitor device (200) for a medical device system (100) has a display element, a display controller /driver coupled to the display element and configured to generate a screen for rendering on the display element. The system further has processing architecture configured to analyze sensor data obtained by the monitor device, the sensor data indicating empirical measurements of a physiological characteristic of a monitored patient, and estimate future measurements of the physiological characteristic based upon the sensor data: The screen comprises a predictive graph (734) of the physiological characteristic that graphically indicates the empirical measurements and the future measurements. In an embodiment the predictive graph (734) comprises indicia of a target zone (740) for the physiological characteristic, the processing architecture being configured to predict whether the future measurements will leave the target zone (740) within a period of time, and to obtain an estimated time (746) corresponding to when the future measurements will leave the target zone (740) and wherein the screen comprises an indicator of the estimated time.
