Abstract: A device and method for non-invasive real-time testing of blood sugar levels in a diabetic patient. Specifically, this invention is directed to an optical device comprising a contact lens having a glucose-sensing optical pattern imprinted, marked, coated or otherwise disposed on or incorporated within the contact lens. The indicator pattern is further comprised of a glucose-sensing coating containing a boronic acid derivative, which reacts in the presence of glucose to create a readable pattern, which can then be correlated to a pre-determined or pre-calibrated blood glucose level. A polarized light source is one method that may be used to read the indicator pattern. The invention is also directed to methods for quantifying blood glucose levels using the inventive optical device and manufacturing methods for disposing the glucose-sensing coating onto, or incorporating it into, the contact lens material.