Analyte sensor faults are detected. Datasets of glucose values sensor electronics are coupled to a glucose sensor in fluid contact with interstitial fluid under a skin surface. Baseline median glucose value and glucose variability values are computed, based on the first dataset. A baseline data point is stored. Evaluation median glucose value and variability are computed, based on the second dataset of glucose values. An evaluation data point is stored. A magnitude of a vector that extends between the baseline data point and the evaluation data point is computed. A component of the magnitude of the vector that is parallel to a hypoglycemia risk contour line is computed and compared to a predefined threshold value. An indication that a sensor fault has been detected if the component is greater than a threshold is displayed.