Participants were recruited between November 2009 and March 2012. Men and women ages 35 years and older were eligible if they had physician-diagnosed DM of more than three months duration, an HbA1c value >7.0% and <9.0% at screening, reported no changes in diabetes medications within the last 3 months, were under the care of a physician for their diabetes, agreed to not change diabetes medications during the trial unless medically indicated, and agreed to avoid pregnancy while in the trial. Participants required a diagnosis of moderate to advanced chronic periodontitis defined as clinical attachment loss and probing depth of at least > 5mm in 2 or more quadrants of the mouth,16 a minimum of 16 natural teeth, and no periodontal treatment in the prior 6 months. Radiographs were used to confirm a diagnosis of chronic periodontitis. Participants needing treatment of extensive tooth decay, tooth abscesses, or other oral infection such as teeth needing root canal therapy, were excluded. Additional exclusion criteria included limited life expectancy, diabetes-related emergency within 30 days, use of non-steroidal anti-inflammatory (NSAID) medications other than daily low dose aspirin (75-325mg), use of immunosuppressive medications, antibiotic use (>7 days within 30 days of enrollment), dialysis, risk of bleeding complications, or heavy alcohol consumption (>3 drinks/day for men and >2/day for women).