Periodontitis is a common chronic inflammatory disease prevalent in diabetes. The aim of this study was to evaluate periodontitis and poor oral hygiene as independent risk factors for either cerebral or myocardial infarction in the diabetes population.

This retrospective cohort study included 17,009 patients with diabetes who had participated in a nationwide health-screening programme, including oral health examination, during 2002–2003 in South Korea. Presence of periodontitis, tooth loss and carious teeth were assessed by professional dentists, and the number of tooth brushings per day was evaluated through self-reported questionnaires. The primary study outcome was the development of cerebral or myocardial infarction, based on International Statistical Classification of Diseases and Related Health Problems, 10^th Revision (ICD-10) codes, up to 31 December 2015.

The study enrolled 17,009 patients with diabetes. Over the mean 11.64 years of follow-up, 1341 patients presented with either cerebral or myocardial infarction. On multivariable Cox proportional hazards regression analysis, presence of periodontitis was an independent risk factor for either cerebral or myocardial infarction [adjusted hazard ratio (HR): 1.17, 95% confidence interval (CI): 1.02–1.34; P = 0.030]. An increased number of carious teeth (≥ 5) was also associated with risk of cerebral or myocardial infarction (adjusted HR: 1.67, 95% CI: 1.20–2.32; P = 0.002), whereas frequent tooth brushing (≥ 2 times/day) was negatively associated with risk of cerebral or myocardial infarction (adjusted HR: 0.79, 95% CI: 0.70–0.90; P < 0.001) compared with tooth brushing ≤ 1 time/day.

Early identification and intervention of periodontal disease may be effective in reducing cardiovascular complications in the diabetes population, and improved oral hygiene would probably be associated with lower cardiovascular risk in diabetes.