The present teachings provide a system for modifying insulin therapy support parameters such as warning limit data and time block data on a hand-held diabetes management device. The system can include a graphical user interface module that creates a graphical user interface having a plurality of bar structures positionable on or between a first line that indicates an upper limit and a second line that illustrates a lower limit. Each of the bar structures can have a first side that indicates a start time of a time window opposite a second side that indicates an end time of the time window and a third side that indicates a lower target value for a blood glucose level opposite a fourth side that indicates an upper target value for the blood glucose level. The bar structures, the first line and the second line can be adjustable by a user input.