A non-invasive device for glucose monitoring through saliva – a paradigm shift in diabetes care

Abstract

Diabetes mellitus requires consistent monitoring to prevent complications, yet conventional self-monitoring of blood glucose (SMBG) through finger-pricking can be cumbersome and invasive. This study explores the potential of a saliva-based glucose monitoring biosensor as a non-invasive alternative. The developed biosensor utilizes immobilized glucose oxidase (GOD), peroxidase (POD) and a chromogenic dye (4-amino antipyrine and phenol) to produce a detectable colour change in response to salivary glucose, which is measured using an RGB sensor. The biosensor demonstrated a detection range of 14.5–213 mg dL⁻¹, with a sensitivity of 10.6 count per mg dL⁻¹ and a response time of under 3 minutes. The biosensor was clinically validated against a commercial glucometer to compare salivary glucose level (SGL) to blood glucose level (BGL), and a strong correlation coefficient between the two methods was established for diabetic patients as 0.97 and 0.9 under fasting and postprandial conditions, respectively. For non-diabetic subjects the values were 0.58 and 0.87. Gender-wise, significant correlations were observed under postprandial conditions for diabetic and non-diabetic males (R² = 0.98, 0.81) and females (R² = 0.89, 0.85). In fasting conditions, diabetic males (R² = 0.98) and females (R² = 0.90), as well as non-diabetic males (R² = 0.74) and females (R² = 0.66), exhibited strong correlations. The biosensor, designed with an improved optical detection system, offers a practical, non-invasive approach for diabetes monitoring, making it particularly suitable for populations seeking alternatives to SMBG.