An electronic controller for an insulin infusion device includes at least one processor device and at least one memory element that cooperate to provide a processor-implemented closed-loop initiation module. The initiation module is operated to obtain a most recent calibration factor for a continuous glucose sensor, the most recent calibration factor representing a first conversion value applicable to convert a first sensor value to a first blood glucose value. The initiation module also obtains a prior calibration factor for the sensor, and calibration timestamp data for the most recent calibration factor and the prior calibration factor. The initiation module regulates entry into a closed-loop operating mode of the insulin infusion device, based on the most recent calibration factor, the prior calibration factor, and the calibration timestamp data.