Glucose levels between the anterior chamber of the eye and blood are correlated based on blood glucose dynamics

Abstract

Glycemic control is essential to manage metabolic diseases such as diabetes. Frequent measurements of systemic glucose levels with prompt managements can prevent organ damages. The eye is a glucose highly demanding organ in our body, and the anterior chamber (AC) in the eye has been suggested for a noninvasive blood glucose monitoring site. However, calculating blood glucose levels from measuring glucose levels in AC has been difficult and unclear. In this study, we aimed to examine glucose levels from AC and find a correlation with blood glucose levels. A total of 30 patients with cataracts (men and women, study 1; 7 and 3, study 2; 9 and 11) who visited Keio University Hospital from 2015 to 2018 and agreed to participate in this study were recruited. Glucose levels from AC and the blood were examined by a UV-hexokinase or H2O2-electrode method before/during the cataract surgery. These values were analyzed with regression analyses depending on the groups (blood glucose-ascending and descending groups). In the blood glucose-descending group, glucose levels from AC were strongly correlated with blood glucose levels (a high R2 value, 0.8636). However, the relatively moderate correlation was seen in the blood glucose-ascending group (a low R2 value, 0.5228). Taken together, we showed different correlation ratios on glucose levels between AC and the blood, based on blood glucose dynamics. Stacking data regarding this issue would enable establishing noninvasive blood glucose monitoring from measuring glucose levels in AC more correctly, which will be helpful for proper and prompt managements for glucose-mediated complications.

Fig 1. Glucose levels from the anterior chamber and blood in subjects with cataracts in Study 1.

Quantitative analyses showed that there was no significant difference in glucose levels between the ‘before/during the surgery’, detected by UV-hexokinase (n = 10) and hydrogen peroxide (H₂O₂)-electrode (n = 8; unfortunately, 2 samples were lost during the surgery) methods. In addition, the levels from the anterior chamber and blood were not significantly different, p > 0.05. Graphs are presented as median with interquartile range, the 25th and 75th percentile. The data were analyzed using Student’s t-test and one-way ANOVA followed by a Bonferroni post hoc test. UV: UV-hexokinase method; H₂O₂: H₂O₂-electrode method.

Fig 2. Visualization of a correlation on glucose levels between the anterior chamber and blood in Study 1 subjects with cataracts based on the values in Table 2.

Dots represent the measured glucose levels. Lines represent the linear fit of the data points. UV: UV-hexokinase method; H₂O₂: H₂O₂-electrode method.

Fig 3. Glucose levels from the anterior chamber and blood in Study 2 subjects with cataracts.

Quantitative analyses showed that there was no significant difference in glucose levels between the ‘before/during the surgery’, detected by the UV-hexokinase method (n = 19 from 20; unfortunately, 1 sample had a measurement error during the surgery, hence, it was excluded). The levels from the anterior chamber were significantly lower than those from the blood, p = 0.0003. T1: the time that the patients entered the operation room (before the surgery), T2: after T1 with a 5 mins interval (before the surgery), T3: the timing of surgery, and T4: after T3 with a 5 mins interval (during the surgery). Graphs are presented as median with interquartile range, the 25th and 75th percentile. The data were analyzed using Student’s t-test and one-way ANOVA followed by a Bonferroni post hoc test.

Fig 4. Visualization of a correlation on glucose levels between the anterior chamber and blood in Study 2 subjects with cataracts based on the values in Table 3.

Dots represent the measured glucose levels. Lines represent the linear fit of the data points. U: up, D: down.

Fig 5. Visualization of a correlation on glucose levels between the anterior chamber and blood in Study 1 and 2 subjects with cataracts based on the values in Table 4.

Dots represent the measured glucose levels. Lines represent the linear fit of the data points. U: up, D: down.