Glutamate, its relation to periodontitis, diabetes and cognition before and after scaling and root planing

This study aimed to correlate levels of salivary and serum glutamate in patients with/without generalized periodontitis and Type 2 diabetes mellitus (T2DM) and to evaluate the effect of scaling and root planing (SRP) on glutamate and cognition. We hypothesized that periodontitis and T2DM are associated with altered glutamate levels and poorer cognitive performance and explored whether SRP-related changes in glutamate relate to cognitive performance. Eighty patients aged 45-70-yr were allocated into four groups: healthy, periodontitis, T2DM and periodontitis with T2DM (n = 20 each). Periodontal parameters, Trail Making Tests (TMT-A and TMT-B) and salivary and serum glutamate levels were recorded at baseline and 1-month post-SRP. Diabetic patients showed higher glutamate levels, poorer periodontal status and prolonged TMT times than non-diabetics at baseline. Glutamate levels decreased significantly after SRP, whereas TMT completion times showed only small reductions. Serum glutamate levels showed a significant, moderate positive correlation with TMT-B scores. Fasting plasma glucose and glutamate were significant predictors of periodontitis. Glutamate was altered but did not mediate the periodontitis-TMT association. In T2DM and non-T2DM patients, serum glutamate was the most accurate marker to differentiate periodontitis. SRP improved periodontal status, reduced glutamate levels and was associated with improved executive function and processing speed.