Methods, apparatuses and systems for back calibration of data from a continuous sensor are provided. The continuous sensor may be calibrated periodically by comparing raw sensor values from the sensor to sensor values obtained from a second sensor, such as a blood glucose meter (BGM). Each calibration may produce a calibration factor. In an aspect, the calibration factor may be applied to sensor values acquired prior to the calibration (i.e., back calibration). In a further aspect, a first calibration and a second calibration may be applied to raw sensor values acquired at a time point between the first calibration and the second calibration. The first and second calibrations may be applied to the raw sensor values by weighted averaging according to the proximity of the first and second calibrations to the acquisition time of the raw sensor value.
