To prevent diabetic complications, strict glucose control and frequent monitoring of blood glucose levels are necessary. However, all currently available methods for blood glucose monitoring, including the finger prick method, are invasive. Therefore, noninvasive blood glucose monitoring approaches have been investigated, but until date, none has been found to be a suitable substitute for direct glucose measurement in blood samples.
We considered monitoring of diabetes-related biomarkers in tears may be the possible methods for diabetes monitoring method. Many studies about tear glucose levels have been reported and tear glucose levels correlate with blood glucose levels. This time, we focused on glycoalbumin (GA) levels, which reflect an average of blood glucose levels over the preceding 2 weeks, and studied the correlation between GA levels in blood and tears..
..The GA 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 this correlation was maintained even after adjustment for age, gender, nephropathy stage, and obesity (P <0.001).
Conclusion: GA in tears was the first measured diabetes-related biomarker. GA 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.
From the above, GA 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.