A method of calibrating an analyte sensor using one or more reference measurements, the method comprising: receiving a first reference analyte measurement (RM1); determining that the RM1 is unexpected; receiving (802 or 902) sensor data from the analyte sensor, wherein the sensor data is the sensor data that is most-recently received from the analyte sensor; after determining that the RM1 is unexpected, receiving (806 or 906) a second reference analyte measurement (RM2); using (804 or 908) the sensor data to calculate a first sensor analyte measurement (SM1) without the RM1 as a calibration point; using (808 or 904) the sensor data to calculate a second sensor analyte measurement (SM2) with the RM1 as a calibration point; determining (810, 910, 1010, or 1110) that one or more of the RM1 and the RM2 are acceptable as calibration points, wherein determining that one or more of the RM1 and the RM2 are acceptable as calibration points comprises comparing the RM2 with the SM1 and comparing the RM2 with the SM2; accepting (812, 814, 912, or 914) one or more of the RM1 and the RM2 as calibration points, wherein accepting one or more of the RM1 and the RM2 as calibration points comprises (a) accepting (814 or 914) both the RM1 and the RM2 as calibration points if determining that one or more of the RM1 and the RM2 are acceptable as calibration points comprises determining that the difference between the RM2 and the SM2 is within a threshold amount and determining that the RM2 is closer to the SM2 than to the SM1 or (b) accepting (812 or 912) the RM2 as a calibration point and not accepting the RM1 as a calibration point if determining that one or more of the RM1 and the RM2 are acceptable as calibration points comprises determining that the difference between the RM2 and the SM1 is within the threshold amount and determining that the RM2 is closer to the SM1 than to the SM2; and calibrating (812, 814, 912, or 914) the analyte sensor using at least one or more of the RM1 and the RM2 as calibration points. receiving a first reference analyte measurement (RM1); determining that the RM1 is unexpected; receiving (802 or 902) sensor data from the analyte sensor, wherein the sensor data is the sensor data that is most-recently received from the analyte sensor; after determining that the RM1 is unexpected, receiving (806 or 906) a second reference analyte measurement (RM2); using (804 or 908) the sensor data to calculate a first sensor analyte measurement (SM1) without the RM1 as a calibration point; using (808 or 904) the sensor data to calculate a second sensor analyte measurement (SM2) with the RM1 as a calibration point; determining (810, 910, 1010, or 1110) that one or more of the RM1 and the RM2 are acceptable as calibration points, wherein determining that one or more of the RM1 and the RM2 are acceptable as calibration points comprises comparing the RM2 with the SM1 and comparing the RM2 with the SM2; accepting (812, 814, 912, or 914) one or more of the RM1 and the RM2 as calibration points, wherein accepting one or more of the RM1 and the RM2 as calibration points comprises (a) accepting (814 or 914) both the RM1 and the RM2 as calibration points if determining that one or more of the RM1 and the RM2 are acceptable as calibration points comprises determining that the difference between the RM2 and the SM2 is within a threshold amount and determining that the RM2 is closer to the SM2 than to the SM1 or (b) accepting (812 or 912) the RM2 as a calibration point and not accepting the RM1 as a calibration point if determining that one or more of the RM1 and the RM2 are acceptable as calibration points comprises determining that the difference between the RM2 and the SM1 is within the threshold amount and determining that the RM2 is closer to the SM1 than to the SM2; and calibrating (812, 814, 912, or 914) the analyte sensor using at least one or more of the RM1 and the RM2 as calibration points. <EOS>