J Clin Periodontol. 2018;45:345–353. wileyonlinelibrary.com/journal/jcpe | 345 © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Accepted: 1 December 2017 DOI: 10.1111/jcpe.12858 RANDOMIZED CLINICAL TRIAL Benefits of non-surgical periodontal treatment in patients with type 2 diabetes mellitus and chronic periodontitis: A randomized controlled trial Elisabet Mauri-Obradors 1 | Alexandra Merlos 2 | Albert Estrugo-Devesa 1 | Enric Jané-Salas 1,3 | José López-López 1,3 | Miguel Viñas 2 1 Department of Dentistry, Dental School, University of Barcelona, Barcelona, Spain 2 Department of Pathology and Experimental Therapeutics, Medical School, IDIBELL- University of Barcelona, Barcelona, Spain 3 Oral Medicine Unit, Department of Dentistry, Faculty of Medicine and Health Sciences (Dental School) and Dental Hospital Barcelona University (University of Barcelona) and Health and Masticatory System Group (Bellvitge Biomedical Research, Institute) IDIBELL, Barcelona, Spain Correspondence José López López, Oral Medicine Unit, Department of Dentistry, Pabellón de Gobierno, and Faculty of Medicine and Health Sciences (Dentistry) Campus of Bellvitge, Barcelona, Spain. Emails: 18575jll@gmail.com, jl.lopez@ub.edu Funding information No external funding, apart from the support of the authors’ institution, was available for this study. Abstract Background: Periodontitis and diabetes are highly prevalent conditions whose asso- ciation has long been recognized. Objective: To evaluate the effect of non-surgical periodontal treatment on serum HbA1c (haemoglobin A1c or glycated haemoglobin) levels in patients with type 2 diabetes. Research Design and Methods: This was a 6-month, single-masked, randomized clini- cal trial based on 90 patients (HbA1c: 7.7% (61 mmol/mol) ± 1.13%) who were ran- domly assigned to either the treatment group (oral hygiene instructions + scaling and root planing using ultrasound and Gracey curettes) or the control group (oral hygiene instructions + supragingival removal of plaque and calculus using ultrasound). Pocket depth, gingival index, and plaque index were assessed at baseline and after 3 and 6 months together with determinations of fasting plasma glucose, HbA1c, and bacterial counts. Results: Treatment significantly improved the periodontal and metabolic parameters (p < .05), whereas in the control group no improvement was observed. These results were consistent with the bacteriological results in most but not all cases. Conclusion: Non-surgical periodontal treatment resulted in a better glycaemic status of type 2 diabetes patients and demonstrated the importance of oral health in their general health. KEYWORDS glycosylated haemoglobin, PCR, periodontal disease, scaling and root planing, type 2 diabetes mellitus 1 | INTRODUCTION Inflammatory periodontal diseases are the most common chronic inflammatory condition, with up to 90% of the world’s population affected. The association of periodontitis with diabetes mellitus has been largely recognized (Pihlstrom, Michalowicz, & Johnson, 2005; Preshaw et al., 2012). Inflammation of the periodontium starts by the formation of a subgingival biofilm, being major risk factors smoking and diabetes (Preshaw et al., 2012). The increased risk of periodontitis for diabetic patients depends on the glycaemic control, as in other complications. Thus, patients with well-controlled glycated haemoglobin (HbA1c; ~7% (53 mmol/mol)) have a risk of periodontitis low increasing expo- nentially as glycaemic control declines (Al-Khabbaz, 2014).