Pilocarpine-stimulated salivary flow rate and salivary glucose concentration in alloxan diabetic rats. Influence of severity and duration of diabetes.

Pilocarpine-stimulated salivary flow rate and glucose concentration were estimated in short-term (1 month) and long-term (12 months) alloxan diabetic rats and in age-matched nondiabetic controls. Diabetic rats had significantly decreased salivary flow rate which was negatively correlated to blood glucose concentration. They also had increased salivary glucose levels, which were positively correlated to blood glucose values, when the blood glucose values were above 15 mmol l-1, suggesting a threshold mechanism for salivary glucose excretion. The long-term diabetic rats had significantly higher salivary flow rates than the short-term diabetics. Insulin therapy in short-term diabetic rats improved the salivary parameters and normalized blood glucose levels, indicating that the salivary abnormalities are reversible - at least in the short-term perspective - and reflect the metabolic derangements of the diabetes. The results suggest that reduced salivary flow rate and increased salivary glucose concentration might be of importance for the development of the periodontal disease and caries seen in diabetic rats.