Non-Surgical Periodontal Therapy and High-Sensitivity C-Reactive Protein in Type 2 Diabetes: Secondary Analysis of a Randomized Trial

Background: Type 2 diabetes mellitus (T2DM) and periodontitis are chronic inflammatory conditions. Periodontitis may amplify low-grade systemic inflammation in people with T2DM. High-sensitivity C-reactive protein (hsCRP) reflects this inflammatory burden, but the effect of non-surgical periodontal therapy (NSPT) on hsCRP in T2DM remains uncertain. Objective: To evaluate whether NSPT changes hsCRP at 3 and 6 months compared with oral hygiene instructions alone in patients with T2DM and periodontitis. Methods: Predefined secondary analysis of a 1:1 parallel-group randomized trial with assessments at baseline, 3 months, and 6 months. Participants received scaling and root planing plus oral hygiene instructions (intervention) or oral hygiene instructions only (control). Fasting hsCRP (mg/L) was analyzed on the log scale using mixed-effects models; effects are presented as exponentiated ratios with 95% confidence intervals. Sensitivity analyses included baseline-adjusted analysis of covariance (ANCOVA) and covariate-adjusted mixed models. An exploratory group-adjusted regression examined associations between periodontal changes and hsCRP change. Results: Eighty-nine participants were randomized (45 control, 44 intervention), with hsCRP available for most participants through 6 months. There was no between-group difference at 3 months (ratio 0.958; 95% CI 0.875–1.049; p=0.358). At 6 months, hsCRP was lower in the NSPT group than in controls (ratio 0.809; 95% CI 0.738–0.887; p<0.001), corresponding to ~19% lower hsCRP; the model-based geometric mean hsCRP at 6 months was 2.66 mg/L versus 3.26 mg/L. Periodontal measures improved more with NSPT, but changes in periodontal measures were not independently associated with hsCRP change after group adjustment. Conclusions: In patients with T2DM and periodontitis, NSPT was associated with lower hsCRP at 6 months, suggesting a potential systemic anti-inflammatory benefit. These findings support periodontal care as part of integrated management in T2DM.