College of Optometry, University of Houston, Houston, TX, USA.
School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.
Clin Exp Optom. 2023 Sep;106(7):752-758. doi: 10.1080/08164622.2022.2111204. Epub 2022 Aug 17.
Tear glucose and insulin are responsible for the health of the ocular surface; thus, it is important for clinicians to detect the tear glucose and insulin using point-of-care methods.
To determine if changes in blood glucose and insulin levels following an oral glucose tolerance test are reflected in the tears and to test the association between gene expression and tear insulin and glucose.
Twenty healthy young adults were enrolled. Basal tears and peripheral blood samples were collected to assess glucose and insulin using a point-of-care glucometer and ELISA assays in fasted subjects, and 1.5 and 3 h after an oral glucose challenge. Conjunctival impression cytology was collected to determine gene expression of insulin receptor (INSR) and glucose transporters (GLUT1 and GLUT4). Changes were examined using non-parametric one-way ANOVA. Spearman tests were conducted to examine associations between variables.
Glucose and insulin levels increased 1.5 h after oral glucose in both blood ( < 0.001) and tears (P < 0.049) and returned to near baseline values after 3 h. There was a positive correlation between glucose levels in the blood and tears (rho = 0.57, < 0.001), but not between blood and tear insulin levels ( = 0.18). Glucose and insulin levels in tears were correlated (rho = 0.32, = 0.048). Tear glucose concentration at 1.5 h after oral glucose was associated with INSR expression (rho = 0.49, = 0.03), and there was a trend with GLUT1 ( = 0.06) but not GLUT4.
Tear glucose reflected blood glucose levels but this correspondence was not observed for insulin. Further studies are required to determine the role of glucose and insulin on the ocular surface in both health and diabetes.
泪液中的葡萄糖和胰岛素负责眼表的健康；因此，临床医生使用即时检测方法检测泪液中的葡萄糖和胰岛素非常重要。
确定口服葡萄糖耐量试验后血糖和胰岛素水平的变化是否反映在泪液中，并测试基因表达与泪液胰岛素和葡萄糖之间的相关性。
纳入 20 名健康的年轻成年人。在空腹状态下，使用即时检测血糖仪和 ELISA 检测采集基础泪液和外周血样，以评估葡萄糖和胰岛素水平，然后在口服葡萄糖负荷后 1.5 和 3 小时采集。收集结膜印迹细胞学样本，以确定胰岛素受体（INSR）和葡萄糖转运体（GLUT1 和 GLUT4）的基因表达。使用非参数单向方差分析检查变化。进行 Spearman 检验以检查变量之间的相关性。
口服葡萄糖后 1.5 小时，血液（ < 0.001）和泪液（P < 0.049）中的葡萄糖和胰岛素水平升高，3 小时后恢复到接近基线值。血液和泪液中的葡萄糖水平之间存在正相关（rho = 0.57， < 0.001），但血液和泪液中的胰岛素水平之间没有相关性（rho = 0.18）。泪液中的葡萄糖和胰岛素水平之间存在相关性（rho = 0.32， = 0.048）。口服葡萄糖后 1.5 小时的泪液葡萄糖浓度与 INSR 表达相关（rho = 0.49， = 0.03），与 GLUT1 呈趋势相关（rho = 0.06），但与 GLUT4 无关。
泪液葡萄糖反映了血糖水平，但这种对应关系在胰岛素中没有观察到。需要进一步的研究来确定葡萄糖和胰岛素在健康和糖尿病患者的眼表中的作用。
