# Non-Invasive and Accurate Blood Glucose Detection Based on an Equivalent Bioimpedance Spectrum
## 8 A Non-Invasive Blood Glucose Detection Experiment
### Personal Blood Glucose Test  
The experiment of personal blood glucose test lasts for 10 h, and it starts in the fasting state. After the first test, the tested person has a nutritional supplement, and then the test repeats every 1 h. In addition, there will be a 30 min lunchtime. The test results are shown in Table 2 and Figure 17.  
Figure 16: Measuring equipment. In Table 2, the K-proximity classification model identified two hyperglycemia samples with biochemical blood glucose values of 6.9 and 7.7. The hyperglycemia sample with a biochemical blood glucose value of 7.7 appears 1 h after lunch, and it meets the physiological diagnostic criteria. On the other hand, the hyperglycemia sample with a biochemical blood glucose value of 6.9 does not strictly meet the physiological diagnostic criteria. According to the manual of the United URI0-26 blood glucose analyzer, the measurement error of biochemical blood glucose can be up to \(\pm\)0.5. Meanwhile, this suspicious sample appears at 2 h after the meal, just within the period that the blood glucose rises rapidly based on physiological knowledge. Therefore, this sample can also be judged as a high blood glucose sample, and it can be concluded that the proposed blood glucose detection model can accurately identify high blood glucose samples in personal tests and achieve type 2 diabetes mellitus detection. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Testing Time**} & \multicolumn{3}{c}{**Classification Model Judgment**} & \multicolumn{3}{c}{**Blood**} & \multicolumn{3}{c}{**Biochemical**} & \multirow{2}{*}{**Absolute Error**} \\  & & & & **Glucose** & & **Blood** & \\  & **European** & **Manhattan** & **Whether It** & **Is High** & **Estimation** & **Clucose** & **Error** \\  & **K-** & **K-** & **Blood** & & & **Level** & \\  & **Approaching** & **Approaching** & **Glucose** & & & & \\ \hline Fasting state & 1 & 1 & no & 4.837 & 4.3 & \(-\)0.537 & 12.48\% \\ \hline
1 h after meal & 1 & 1 & no & 5.621 & 5.4 & \(-\)0.221 & 4.09\% \\ \hline
2 h after meal & 0 & 0 & Yes & 7.986 & 6.9 & \(-\)1.086 & 15.73\% \\ \hline
3 h after meal & 1 & 1 & no & 6.032 & 6.5 & 0.468 & 7.20\% \\ \hline
4 h after meal & 1 & 0 & no & 6.121 & 5.8 & \(-\)0.321 & 5.53\% \\ \hline
1 h after lunch & 0 & 0 & Yes & 8.775 & 7.7 & \(-\)1.075 & 13.96\% \\ \hline
2 h after lunch & 1 & 0 & no & 6.668 & 6.5 & \(-\)0.168 & 2.58\% \\ \hline
3 h after lunch & 0 & 1 & no & 6.325 & 6.1 & \(-\)0.225 & 3.68\% \\ \hline
4 h after lunch & 1 & 1 & no & 5.378 & 5.8 & 0.422 & 7.27\% \\ \hline Fasting before dinner & 1 & 1 & no & 5.253 & 5.6 & 0.347 & 6.19\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Single-person blood glucose experiment and blood glucose estimation. Figure 17: Comparison of data from the second single-person blood glucose fluctuation experiment. Further analysis of the data in Table 2 shows that large errors are found in hypoglycemia (biochemical blood glucose value of 4.3) and near-threshold (biochemical blood glucose value of 6.9) samples. As pointed out by physiological knowledge, when the human body is in a water-deficient state after exercise, there will be a temporary decrease in impedance, and the human body in a \"fasting state\" has the same characteristics as that of a \"water-deficient state\". Furthermore, in the regression fitting Equation (7), the impedance value has a negative correlation with blood glucose estimation. As a result, the impedance reduction causes a positive error in blood glucose estimation. Therefore, it is necessary to drink an appropriate amount of water before the experiment to ensure that the human body is only in an empty stomach state so as to reduce the measurement error caused by \"water shortage\". In Table 2, the absolute error of blood glucose estimation in the \"fasting state\" is 0.53. In subsequent tests, the impedance in either the \"hydration supplement\" or \"water shortage state\" case is tested, respectively.