Correlation of Salivary Glucose Levels with Blood Glucose Levels in Patients with Diabetes Mellitus: A Cross-sectional Study from KLE’s Dr. Prabhakar Kore Hospital and Medical Research Centre, Belagavi, Karnataka

Background: Diabetes mellitus (DM) is a common chronic condition that requires regular monitoring of blood glucose levels. Saliva contains various biomarkers that can reflect physiological changes in the body, indicating its potential as an alternative source for glucose monitoring. Objective: This study aimed to correlate salivary glucose levels with blood glucose levels in patients with DM at a tertiary care center in North Karnataka. Materials and Methods: A cross-sectional, descriptive observational study was conducted over a 1-year period, involving 100 patients diagnosed with type 2 DM. Data on fasting and postprandial salivary and blood glucose levels, as well as Glycated hemoglobin (HbA1c), were collected. Pearson correlation coefficients were used to evaluate the relationship between salivary and blood glucose levels. P < 0.05 was considered statistically significant. Results: The mean age was 60.6 ± 13.01 years, with 62% males. The majority of the study population was over 60 years old (47%), while those aged 51–60 years comprised 32%. The mean fasting salivary glucose (FSG) was 5.22 ± 3.45 mg/dL, and postprandial salivary glucose (PPSG) was 8.34 ± 4.08 mg/dL. The mean fasting blood glucose was 141.4 ± 41.2 mg/dL, postprandial blood glucose was 213.8 ± 51.6 mg/dL, and the mean HbA1c was 8.2% ±1.7%. Significant positive correlations were observed between FSG levels and both fasting capillary and blood glucose levels ( P < 0.05). Similarly, significant correlations were found between PPSG levels and postprandial capillary and blood glucose levels ( P < 0.05). FSG also showed a positive correlation with HbA1c, though it was not statistically significant ( P > 0.05), while PPSG had a significant correlation with HbA1c ( P < 0.05). PPSG levels were significantly higher in patients with severe nonproliferative diabetic retinopathy compared to those with mild or moderate forms ( P < 0.05). In contrast, differences in FSG across retinopathy grades were not significant ( P > 0.05). Conclusion: The findings indicate that salivary glucose levels are significantly correlated with blood glucose levels in patients with DM, suggesting that saliva can be used as a noninvasive method for glucose measurement.