<qa>  What is the primary cause of the CG patients receiving salvage therapy?Methods: This study is a 6-month, single-masked, randomized clinical trial.A total of 90 patients with diabetes and chronic generalized periodontal disease will be randomly divided into 2 groups: Treatment Group TG Oral Hygiene Instructions OHI scaling and root planing RAR using ultrasound device and Gracey curettes; Control Group CG OHI supragingival removal of plaque and calculus with ultrasonic device. CG patients receive salvage therapy if a significant worsening of their periodontal status and or metabolic observed. Periodontal assesment probing pocket depth PPD, gingival index GI, and plaque index PI and systemic assesment random blood sugar, glycosylated hemoglobin HbA1C, and salivary cytokines and bacterial asessment at baseline and 3, 6 months after treatment is performed. There will be a single examiner, blind and calibrated to improve reproducibility. The investigators hypothesis is that non-surgical periodontal treatment reduces HbA1c, improving metabolic control in patients with DM 