Glucose concentration in parotid saliva after glucose/food intake in individuals with glucose intolerance and diabetes mellitus

The concentration of glucose in parotid saliva was measured after glucose/food intake in two separate studies (A and B). In Study A, 10 subjects with impaired glucose tolerance (IGT), 10 subjects with newly diagnosed Type 2 diabetes and 12 healthy controls were included. Study B comprised 15 subjects with Type 1 or Type 2 diabetes on insulin treatment, nine subjects with Type 2 diabetes on treatment with oral antidiabetic drugs and 12 healthy controls. After a 10-h overnight fast, the participants in Study A were given a 75 g oral glucose load, while those in Study B received a standardized breakfast. Citric acid-stimulated parotid saliva was collected up to two hours after the intake. Capillary blood and gingival exudate samples were also taken. On the basis of AUC values (area under the curve over baseline), the glucose concentration in parotid saliva increased significantly in individuals with IGT and Type 2 diabetes compared with controls in Study A and in diabetic patients on treatment with insulin and oral antidiabetic drugs compared with controls in Study B. No effect by the glucose/food intake on the glucose concentration in gingival exudate could be demonstrated in any of the studies. The correlation coefficient between the AUC values of glucose in saliva and blood, when all three groups were combined, was 0.38 in Study A and 0.52 in Study B. It is concluded that the concentration of glucose in parotid saliva is elevated at least 2 h after glucose/food intake in individuals with both IGT and manifest diabetes mellitus.