Oral glucose tolerance test in unstimulated saliva of healthy individuals

Objective: The aim of this study was to investigate oral glucose tolerance test (OGTT) in unstimulated whole saliva as a diagnostic specimen in clinical practice for detection of diabetes mellitus (DM). Materials and Methods: An interventional study was carried out in 30 apparently healthy individuals aged 24-59 years. Serum and saliva samples were obtained in fasting, 1 h and 2 h after glucose intake (75 g). Glucose concentration was determined by enzymatic colorimetric glucose oxidase-prostatic acid phosphatase assay. Statistical analysis of the repeated ANOVA (followed Bonferroni post-hoc test) and Pearson correlation coefficient were used. Results: The mean serum glucose concentration was significantly higher 1 h after glucose intake (152.32 ± 31.06) than both fasting state (106.38 ± 41.08; P < 0.001) and 2 h after glucose intake (125.21 ± 51.71; P < 0.001). Saliva glucose was also significantly higher 1 h after glucose intake (5.46 ± 2.41) than both fasting state (2.84 ± 1.46; P < 0.001) and 2 h after glucose intake (4.01 ± 1.91; P < 0.001). There were significant positive correlation between saliva and serum glucose concentration in fasting state (r = 0.502; P = 0.044), 1 h (r = 0.756; P = 0.0001), and 2 h (r = 0.543; P = 0.023) after oral glucose intake. Conclusion: It seems that unstimulated saliva can be used as an alternative to serum for diagnosis of DM in OGTT.