Scientists at the University of Michigan have developed an electrochemical glucometer that has shown a high correlation with traditional blood glucose testing in rabbits, but uses only 4–5 μL of tears.
Although clearly more comforting than pricking fingers, we’ll have to see if we want type 1 kids and type 2 demented elderly sticking pipettes into their eyeballs.
Some details about the new sensor from the study abstract in Analytical Chemistry:
An amperometric needle-type electrochemical glucose sensor intended for tear glucose measurements is described and employed in conjunction with a 0.84 mm i.d. capillary tube to collect microliter volumes of tear fluid. The sensor is based on immobilizing glucose oxidase on a 0.25 mm o.d. platinum/iridium (Pt/Ir) wire and anodically detecting the liberated hydrogen peroxide from the enzymatic reaction. Inner layers of Nafion and an electropolymerized film of 1,3-diaminobenzene/resorcinol greatly enhance the selectivity for glucose over potential interferences in tear fluid, including ascorbic acid and uric acid. Further, the new sensor is optimized to achieve very low detection limits of 1.5 ± 0.4 μM of glucose (S/N = 3) that is required to monitor glucose levels in tear fluid with a glucose sensitivity of 0.032 ± 0.02 nA/μM (n = 6). Only 4–5 μL of tear fluid in the capillary tube is required when the needle sensor is inserted into the capillary. The glucose sensor was employed to measure tear glucose levels in anesthetized rabbits over an 8 h period while also measuring the blood glucose values.
American Chemical Society press release: Tear drops may rival blood drops in testing blood sugar in diabetes
Abstract in Analytical Chemistry: Measurement of Tear Glucose Levels with Amperometric Glucose Biosensor/Capillary Tube Configuration