1. A method for calibrating an optical coherence tomography (OCT) sensor by correlating OCT measurements with blood analyte measurements, comprising: receiving blood analyte measurements from a subject over a period of time; obtaining OCT measurements from biological tissue of the subject using an OCT sensor such that at least one OCT measurement is associated with each blood analyte measurement, each of the OCT measurements capable of being represented as a plot of intensity against depth of the biological tissue; computing intensity differences between at least two of the obtained OCT measurements at corresponding depths to generate an intensity difference plot; selecting, based on the intensity difference plot, a portion of each of the OCT measurements correlating with the associated blood analyte measurement, the portion including a selected depth; and determining, using a processor, a calibration relationship for the OCT sensor using the selected portions of the OCT measurements and the associated blood analyte measurements.