The present invention relates to the use of Raman spectroscopy for quantitative, non-invasive transcutaneous measurement of blood analytes, such as glucose. Raman spectroscopy is used to measure glucose transcutaneously, in patients whose blood glucose levels were monitored. Raman spectra were collected transcutaneously along with glucose reference values provided by standard capillary blood analysis. A partial least squares calibration was created from the data from each subject and validated using leave-one-out cross validation.