# Unstimulated Parotid Saliva Is a Better Method for Blood Glucose Prediction
## 3 Results
### Sample Characteristics  
Table 2 shows saliva glucose levels of the studied groups; the SFR in the unstimulated parotid saliva was the smallest, followed by the USS, and the largest was UWS. Stimulation of citric acid could also increase the SFR.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **NaCl** \\ **Concentration** \\ \end{tabular} } & \multicolumn{3}{c}{**Absorbance of Different Glucose**} & \multirow{2}{*}{**R\({}^{2}\)**} & \multirow{2}{*}{**Sy. x**} \\ \cline{2-2} \cline{4-4}  & & **0.5 mg/dL** & & **1 mg/dL** & & **1.5 mg/dL** \\ \hline
1 mg/dL & 0.268 \(\pm\) 0.05 & 0.572 \(\pm\) 0.15 & 0.762 \(\pm\) 0.17 & 0.9826 & 0.04654 \\ \hline
3 mg/dL & 0.264 \(\pm\) 0.09 & 0.474 \(\pm\) 0.13 & 0.836 \(\pm\) 0.28 & 0.977 & 0.06205 \\ \hline
5 mg/dL & 0.28 \(\pm\) 0.09 & 0.558 \(\pm\) 0.12 & 0.826 \(\pm\) 0.27 & 0.9999 ** & 0.004082 ** \\ \hline
7 mg/dL & 0.3 \(\pm\) 0.05 & 0.654 \(\pm\) 0.28 & 0.75 \(\pm\) 0.22 & 0.9012 & 0.1053 \\ \hline
9 mg/dL & 0.238 \(\pm\) 0.03 & 0.564 \(\pm\) 015 & 0.902 \(\pm\) 0.23 & 0.9999 * & 0.004899 * \\ \hline
11 mg/dL & 0.262 \(\pm\) 0.15 & 0.654 \(\pm\) 0.25 & 1.302 \(\pm\) 0.61 & 0.9802 & 0.1045 \\ \hline
13 mg/dL & 0.25 \(\pm\) 0.15 & 0.592 \(\pm\) 0.31 & 0.992 \(\pm\) 0.45 & 0.998 & 0.02368 \\ \hline
15 mg/dL & 0.266 \(\pm\) 0.07 & 0.504 \(\pm\) 0.21 & 0.782 \(\pm\) 0.36 & 0.998 & 0.01633 \\ \hline
17 mg/dL & 0.368 \(\pm\) 0.19 & 0.53 \(\pm\) 0.19 & 0.872 \(\pm\) 0.24 & 0.9592 & 0.07348 \\ \hline
19 mg/dL & 0.254 \(\pm\) 0.21 & 0.506 \(\pm\) 0.11 & 0.744 \(\pm\) 0.33 & 0.9997 & 0.005715 \\ \hline \hline \end{tabular}  
* Indicates the better result, ** Indicates the best result.  
\end{table}
Table 1: Correlation between different NaCl concentration and absorbance with 520 nm wavelengths and pH 6.5.  
Figure 2: The influence of wavelength and pH on the absorbance of the sample. The red squared highlighting a value is the best result.  
Figure 4 shows absorbance of saliva glucose concentration at different saliva collection methods. It can be seen that the saliva concentration of unstimulated parotid saliva was significantly higher than the other five methods. At the same time, the stimulated saliva glucose concentration was significantly lower than the unstimulated saliva glucose concentration. In general, the amount of saliva collected by the stimulated method was much greater than that of the unstimulated method, but the stimulated saliva glucose concentration was lower than the unstimulated saliva glucose concentration.  
Figure 4: Absorbance of saliva glucose concentration at different saliva collection methods.  
Figure 3: Standard curve of absorbance values of different concentrations of glucose.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Collection** & **UWS** & **SWS** & **UPS** & **SPS** & **USS** & **SSS** \\ \hline SFR (\(\mu\)L/min) & 1347 \(\pm\) 322 & 1632 \(\pm\) 314 & 113 \(\pm\) 21 & 145 \(\pm\) 55 & 413 \(\pm\) 89 & 571 \(\pm\) 111 \\ \hline \hline \end{tabular} SD: Standard Deviation, respectively denoted as unstimulated whole saliva (UWS), stimulated whole saliva (SWS), stimulated parotid saliva (SPS), unstimulated parotid saliva (UPS), unstimulated sublingual/submandibular saliva (USS), and stimulated sublingual/submandibular saliva (SSS).  
\end{table}
Table 2: Saliva glucose levels of the studied groups.