1. A method of estimating blood analyte concentrations using an optical coherence tomography (OCT) device, the method comprising: computing intensity differences between at least two OCT scans of biological tissue to generate an intensity difference plot; selecting, based on portions of the intensity difference plot having large changes in intensity, corresponding portions of the at least two OCT scans correlating with at least two blood analyte measurements, the at least two blood analyte measurements obtained independently from the at least two OCT scans; generating, using a processor, calibration data for an OCT device based in part on the selected portions of the OCT scans; using the calibration data to calibrate subsequent OCT scans; and estimating blood analyte concentrations from the subsequent OCT scans.