Tear samples may help monitor blood sugar in Diabetes: Study
It is well known that strict blood sugar control and frequent monitoring of blood sugar levels are necessary to prevent diabetic complications.
In order to achieve this, Diabetes patients have to test their blood sugar several times a day, usually by pricking their finger with a lancet. This uncomfortable and painful process for many may result in less frequent testing and consequently a poorer control of blood sugar levels.
Scientists have been looking for needle-free alternatives to make the lives of millions of diabetics easier, but until date, none has been found to be a suitable substitute for direct glucose measurement in blood samples.
Researchers at Graduate School of Medicine at the University of Tokyo considered monitoring of diabetes-related biomarkers in tears may be the possible methods for diabetes monitoring method. They found in a new study that measuring substance in tear could be a future way for those with diabetes to monitor their blood sugar levels noninvasively. The substance is glycated albumin (glycoalbumin, GA) that reflects the 2-week average blood sugar level like fructosamine.
The findings were revealed at poster presentation at the virtual annual meeting of the European Association for the Study of Diabetes.
The researchers feel that this could be a better biomarker for detecting earlier changes in blood sugar than glycated hemoglobin (HbA1c) because it reflects changes in blood sugar over the preceding 2-3 months.
The researchers conducted a trial in 100-patients and found that levels of GA in tears strongly correlated (r = .722; P < .001) with those in the blood.
Dr. Aihara and associates collected tear and blood samples at the same time. They assessed tear samples using liquid chromatography (LC) and mass spectrometry (MS). An enzymic method was used to measure GA levels in blood. All the statistical analyses were carried out using the Statistical Package for Social Sciences (SPSS) version 22.0 (IBM Corp.).
The glycated albumin levels in tear samples of 99 out of 100 subjects was appropriately measured by LC-MS/MS. GA levels in blood and tear samples were significantly correlated (P <0.001).
Multiple regression analysis revealed that the correlation between GA levels in tears and in blood was maintained even after adjustment for age, gender, nephropathy stage, and obesity (P < .001). The results obtained from the tests were thought unlikely to be affected by any changes in the concentration or dilution of tear samples.
The researchers concluded that glycated albumin in tears was the first measured diabetes-related biomarker. Glycated albumin levels in tears were strongly correlated with those in blood, considering various factors such as age, gender, nephropathy stage, and obesity. As GA value is a ratio, GA levels in tears were not thought to be influenced by dilution or concentration of tears and showed strong correlation with those in blood.
Therefore glycated albumin in tears could be a diabetes-related biomarker that can be measured noninvasively. In the future, we plan to optimize measurement conditions and develop measurement equipment, and to verify the effectiveness and usefulness of diabetes monitoring methods.
Tears not only protect the eye, they contain a variety of large proteins, and their composition can change with disease. Keeping this in mind researchers have been looking at their usefulness in helping find biomarkers for Parkinson's disease and diabetic peripheral neuropathy.
SOURCE: Aihara M et al. EASD 2020, poster presentation 624.