Effect of non-surgical periodontal therapy on insulin resistance and insulin sensitivity among individuals with borderline diabetes: A randomized controlled trial

Objective: To investigate the effect of non-surgical periodontal therapy on insulin resistance and sensitivity among individuals with borderline diabetes not receiving medications. Methods: A crossover, randomized controlled trial was conducted among participants with borderline diabetes diagnosed by a 75-g oral glucose tolerance test. Participants were randomly assigned to either an early or later intervention group. The early intervention group underwent non-surgical periodontal therapy of scaling and root planing during the first 6 months, followed by a 6-month non-intervention period. The order was reversed in the later intervention group. Primary outcomes included: fasting or post-load serum glucose and insulin, body mass index (BMI), HOMA-IR, HOMA-β, and Matsuda Index. Results: Seventy-four participants were randomized, and 71 participants completed the trial. There were no significant differences between groups in glucose and insulin concentrations during the intervention and non-intervention periods. When analyzed within groups by median-split of bleeding on probing (BOP) levels before intervention, the lower BOP group showed improved changes in BMI, HOMA-IR, HOMA-β, and Matsuda Index (P < 0.05). Further, we observed a positive correlation between baseline BOP and change in BMI (P = 0.06). Change in BMI was positively correlated with changes in HbA_1c, HOMA-IR, and HOMA-β (P < 0.05), and inversely correlated with change in Matsuda Index (P = 0.001). Conclusions: Periodontal therapy had no significant effect on markers related to insulin and glucose metabolism among individuals with borderline diabetes. However, participants with a lower BOP (%) showed significant improvements in BMI, fasting serum insulin, HOMA-IR, HOMA-β and Matsuda Index. Clinical significance: Among individuals diagnosed with borderline diabetes, those who had <37% of a lower BOP (%) showed potential improvements in BMI, fasting serum insulin, HOMA-IR, HOMA-β and Matsuda Index following non-surgical periodontal therapy.