Fasting salivary glucose levels is not a better measure for identifying diabetes mellitus than serum or capillary blood glucose levels: comparison in a Ghanaian population

Abstract

Aims/introduction: We compared the diagnostic performance and correlation between salivary, serum and capillary blood glucose of diabetes and non-diabetes patients. Early detection of diabetes mellitus (DM) contributes to the prevention of complications and management. Materials and methods: This case-control study was conducted among a total of 138 participants comprising 79 newly diagnosed diabetes patients (cases) and 59 non-diabetes patients (controls). Fasting salivary glucose (FSLG), fasting serum glucose (FSEG) levels and fasting capillary whole blood glucose (FCWBG) level were assayed for each participant. Results: The mean FSLG, FSEG and FCWBG levels were significantly higher among the cases compared to controls (p < 0.0001). There was a significant mean difference between the levels of FSLG vs. FSEG (p < 0.0001) and FSLG vs. FCWBG (p < 0.0001) but not levels of FSEG vs. FCWBG (p > 0.05) in both cases and controls. A positive correlation was observed between FSLG and FSEG (r ¼ 0.89; p < 0.0001) and FCWBG (r ¼ 0.87; p < 0.0001). At the cut- off value >6.8 mmol/l for FSEG, a sensitivity of 99%, specificity of 100.0% and area under the curve (AUC) of 98.8% was observed for predicting DM while a sensitivity of 80%, specificity of 95% and AUC of 91.0% was observed for FSLG at a cut-off value >0.5 mmol/l. At the cut-off value >6.9 mmol/l for FCWBG, a sensitivity of 100.0%, specificity of 100.0% and AUC of 100.0% was observed for predicting DM. Conclusion: Fasting salivary glucose (FSLG) levels increased with increasing blood glucose levels. However, it does not generate enough diagnostic and predictive accuracy compared to capillary whole blood glucose which less invasive.