One study [24] randomized 34 participants (17 receiving SDD and 17 receiving placebo) with chronic periodontitis and type 2 diabetes; although MMP-8 decreased significantly between baseline and three months among the SDD group while an increase was observed in the placebo group, there was no significant difference between the two groups according to the study authors. The gene discussed is MMP8; the disease is type 2 diabetes mellitus.