Non-invasive monitoring by measuring glycated albumin in tears

Tears may offer a new opportunity for monitoring blood glucose in diabetic patients. It has been shown that measuring glycated albumin (GA) in tears is feasible and that the GA in tears accurately reflects the levels of GA in blood.

GA is a biomarker which corresponds to the average level of blood glucose over 2 weeks. HbA1c reflects changes over a longer period of time (2 to 3 months), so GA may be a better biomarker for detecting earlier changes in blood glucose. This prompted Japanese researchers to determine the feasibility of measuring the level of GA in tears of 100 patients; the findings were presented by Dr Masakazu Aihara (University of Tokyo, Japan) [1].

Tear and blood samples were collected from the participants at the same time. GA in tear samples was measured by liquid chromatography and mass spectrometry, whilst an enzyme method was used to assay the level of GA in blood. After multiple regression analysis, it was shown that the correlation between GA in tears and in blood was maintained, even when researchers adjusted for age, gender, nephropathy stage, and obesity (r=0.722; P<0.001).

These findings open up new possibilities to non-invasively monitor patients’ blood glucose levels. Researchers are attempting to improve the method by which tear samples are collected and to reduce the volume of tears required for analysis. The current method involves collecting tears with a dropper, and 100 µL of tear fluid is needed to accurately measure GA concentration. Other studies are being done to test this method for monitoring the effect of glucose-lowering treatments.

1. Aihara M, et al. Development of noninvasive diabetes monitoring method using tear samples. EASD 2020. Abstract #644.