Saliva in non-insulin-dependent diabetic patients and control subjects: The role of the autonomic nervous system.

Objective: The purpose of this investigation was to study the flow rate and organic constituents of whole saliva in relation to autonomic nervous function in patients with non-insulin-dependent diabetes.

Study Design: We studied the associations of saliva factors and autonomic nervous function in 45 patients with non-insulin-dependent diabetes (mean age, 68 +/- 6 years) and 77 control subjects (mean age, 67 +/- 5 years). The metabolic evolution was well known over a 10-year period from the time of diagnosis. Resting and paraffin-wax-stimulated whole saliva samples were collected and analyzed. Autonomic nervous function was evaluated by measuring heart rate variation during deep breathing and change in systolic blood pressure during orthostatic testing and by means of power spectral analysis of heart rate variability while standing. The effect of drugs used on saliva was also studied.

Results: No difference was seen in flow rate between the patients with diabetes and the control subjects; resting flow rates were 0.3 +/- 0.3 ml/min in the patients with diabetes and 0.3 +/- 0.2 ml/min in the control subjects, and stimulated flow rates were 1.2 +/- 1.4 ml/min in the patients with diabetes and 1.2 +/- 0.8 ml/min in the control subjects. The number of drugs used daily correlated with salivary flow rates of the control subjects (p < 0.001) but not with flow rates of the patients with diabetes. The effect of xerogenic medication on salivary flow rates was stronger in patients with diabetes than in control subjects, however. There were no statistically significant differences between patients with diabetes and control subjects in the organic constituents of saliva. The stimulated saliva secretion was associated with total power (rs = 0.343; p = 0.035), medium-frequency power (rs = 0.375; p = 0.020), and high-frequency power (rs = 0.414; p = 0.010) of heart rate variability in patients with diabetes.

Conclusion: Saliva secretion might be more affected by xerogenic drugs and autonomic nervous dysfunction in patients with non-insulin-dependent diabetes than in nondiabetic control subjects.