DEVELOPMENT OF NON-INVASIVE BLOOD GLUCOSE MEASUREMENT BY FOURIER TRANSFORM INFRARED SPECTROSOPIC ANALYSIS THROUGH THE MUCOUS MEMBRANE OF THE LIP USING CHALCOGENIDE OPTICAL FIBER SYSTEM

采用傅里叶变换红外光谱（FT-IR）与衰减全反射（ATR）棱镜，研究了通过唇粘膜的无创血糖测量。为实现ATR棱镜与唇部粘膜的易附着和易控制附着压力，采用光纤尖端内置ATR棱镜的硫系光纤。在通过唇粘膜的光谱中发现了与葡萄糖溶液相同的葡萄糖特异性峰，波数为1080和1033 cm^<-1>。当ATR棱镜对唇部粘膜施加6.7×10^3 dyn/cm^2的恒定压力时，一天内测量值的变异系数为3.8，日常测量值的变异系数为5.4%。为了消除基线漂移和葡萄糖以外的身体成分的干扰，作为个体特征，评估了餐后状态下测量的光谱与空腹状态下获得的背景光谱在1080 cm-1处的吸收差。静脉脉冲注射葡萄糖后，1080 cm^<-1>处的吸光度差异与血糖浓度变化的时间延迟为4分钟。在日常血糖监测中，吸收度差异与空腹以上血糖浓度升高呈极显著相关（r=0.920, p<0.01）。这些实验表明，利用硫系光纤的红外光谱可以用于临床无创监测通过唇粘膜的葡萄糖。

Using Fourier transform infrared (FT-IR) spectroscopy with attenuated total reflection (ATR) prism, non-invasive blood glucose measurement through the mucous membrane of the lip was investigated. To achieve easy attachment and easy control of attachment pressure of ATR prism to the mucous membrane of the lip, the chalcogenide optical fiber with ATR prism built in the tip of the optical fiber was used. The same glucose specific peaks at wave numbers of 1080 and 1033 cm^<-1> as glucose solutions were found in a spectrum through the mucous membrane of the lip. With a constant pressure of ATR prism to the mucous membrane of the lip at 6.7×10^3 dyn/cm^2, coefficients of variation of measurements within a day and of day-to-day measurements were 3.8 and 5.4%, respectively. To eliminate baseline drifts and interference of body constituents other than glucose, the difference absorbancess at 1080 cm-1 between spectra measured at postprandial state and background spectrum obtained at fasting state as an individual characteristic were evaluated. Following intravenous pulsatile injection of glucose, the difference absorbancess at 1080 cm^<-1> nicely followed to the changes in blood glucose concentrations with a time delay of 4 minutes. In daily blood glucose monitoring, highly significant correlation between the difference absorbancess and increases in blood glucose concentrations above fasting level was obtained (r=0.920, p<0.01). From these experiments, it was suggested that FT-IR spectroscopy with the chalcogenide optical fiber could be useful clinically for non-invasive monitoring of glucose through the mucous membrane of the lip.