A device for monitoring a diabetic patient includes continuous glucose monitoring system that is configured to generate glucose data indicative of the patient's actual glucose level. An continuous subcutaneous insulin infusion pump is configured to inject insulin into the patient and that is configured to generate insulin data regarding when and how much insulin has been injected into the patient. A processor, programmed with a discrete-time reiterative filter, calculates a predicted glucose level corresponding to a predicted glucose level currently expected to be sensed by the continuous glucose monitoring system, based on the insulin data and the glucose data over time and is also programed to generate an alert when the actual glucose level is different from the predicted glucose level by a predetermined amount. An alert generating device is coupled to the processor and is configured to generate an aesthetically-sensible event corresponding to the generation of the alert.