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What Might Be Better Than CGM?

Jul 14, 2020
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Maya Palmer, PharmD. Candidate, Florida A&M University College of Pharmacy

Saliva test for diabetes may be able to provide an alternative form of glucose management.

Blood glucose testing remains a crucial component of diabetes management. Patients with diabetes know that frequent blood glucose monitoring is necessary to maintain levels in range. They are also aware of the repetitive finger-prick blood tests that accompany monitoring. Research suggests that saliva testing may be a more cost-effective and painless alternative. 


Lead researcher, Dr. Matthew Baker, stated that “saliva reflects several physiological functions of the body, such as emotional, hormonal, nutritional and metabolic, and so its biomarkers could be an alternative to blood for robust early detection and monitoring of diabetes.” Also, collecting saliva would be a less invasive and more convenient option than collecting blood. This study used Fourier transform infrared (ATR-FTIR) spectroscopy to observe saliva of three sets of laboratory subjects: non-diabetic, diabetic, and insulin-treated diabetic. The aim was to identify specific spectral biomarkers that were suitable to monitor blood glucose. 

Researchers tested a group of diabetes-induced, male Wistar rats. Initial classifications of the rats were either diabetic if they had hyperglycemia (> 250mg/dl), or non-diabetic. Days later, a group of diabetic rats received insulin treatment. To ensure the diabetes induction and insulin treatment were successful, researchers observed and compared water intake, weight gain, plasma glucose, urine volume, and urine glucose concentrations. Their saliva was collected next and further analyzed. Researchers used a one-way analysis of variance (ANOVA) to investigate the saliva’s spectral band areas. A receiving operating characteristic (ROC) curve analysis evaluated the accuracy of the highlighted biomarkers’ diagnostic and monitoring abilities under normal glycemic and hypoglycemic conditions. A hierarchical cluster analysis (HCA) tested the specific saliva biomarkers to classify normoglycemic, diabetic, and insulin-treatment subjects. 

Diabetic rats initially showed higher plasma glucose (p < 0.05), and urine glucose concentration (p <0.05) compared with non-diabetic rats. They also showed a reduction in weight gain (p <0.05) and more water intake (p < 0.05) versus the non-diabetic group. For insulin-treated rats, there was a reduction in plasma glucose (p < 0.5), urine volume (p < 0.05), and an increase in weight gain (p < 0.05). These findings confirmed successful diabetes induction and insulin treatment. A decrease (p < 0.05) in absorbance was evident at both 1452cm-1 and 83mcm-1 wavenumbers in diabetes-induced rats compared to non-diabetic rats. In contrast, insulin-treated rats showed a reversal of this decline. 1452cm-1 and 83mcm-1 were two spectral biomarkers discovered to have the strongest correlation to glycemia from these results. Both biomarkers proved to differentiate between normal glycemic and hypoglycemic conditions. They also had a sensitivity and specificity of 100% in the ROC analysis. After the HCA was completed, the biomarkers obtained an accuracy of 95.2% during the classifying processes. Diabetic and non-diabetic rats were 100% correctly separated, and just one insulin-treated diabetic rat was incorrectly grouped as non-diabetic. 

Although this study confirms biomarkers that promote the use of saliva in diabetes monitoring, further investigation is needed to determine if the same biomarkers are valid in humans. Furthermore, both biomarkers should ideally have the capability to differentiate drug treatments and various levels of glycemia. Further studies are needed to determine this level of advancement. More research is also required using variations of saliva monitoring. The presence of glucose in food poses as a limiting factor that could quicken changes in saliva glucose concentration and alter the monitoring. Overall, the approach of using saliva to test blood glucose was able to further transpire into technology. The Saliva Glucose Biosensor has been invented to use saliva to measure glucose instead of blood and overall improve the quality of life for patients by eliminating the invasive needle alternative. The biosensor provides real-time data that would be electronically transmitted to a smart device and further sent to an electronic medical record or caregiver. This system is still awaiting regulatory approval; however, it can significantly improve the ease of diabetes monitoring and make management more personalized for patients.  

Practice Pearls:

  • Saliva has been tested and proven to be an alternative to blood when monitoring diabetes.
  • Using a saliva test is less invasive, cost-efficient, and more convenient for diabetes patients as compared to using blood.
  • This study used saliva biomarkers from rats—further studies are needed to validate the efficacy in humans.


Caixeta, D.c., et al. “Salivary Molecular Spectroscopy: A Sustainable, Rapid and Non-Invasive Monitoring Tool for Diabetes Mellitus during Insulin Treatment.” PLOS ONE, March 17. 2020, pp. 1–18., doi:10.1101/781096.


Maya Palmer, PharmD. Candidate, Florida A&M University College of Pharmacy


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