Impact of Glycaemic Control on the Number of Teeth Remaining: A Cross-Sectional Analysis Using a Database Containing Japanese Employment-Based Health Insurance and Check-Up Data

Abstract

Background: Diabetes mellitus (DM) is a well-known risk factor for periodontal disease, independent of age and smoking. However, the relationship between glycaemic control and tooth loss has not been well characterized. We aimed to determine whether the haemoglobin A1c (HbA1c) level is associated with the number of teeth remaining. Methods: This was a cross-sectional study of 233,567 individuals aged 20–74 years in a database comprising health insurance claim and health check-up data that was collected between April 1, 2015 and March 31, 2016. The participants were allocated to five groups according to their HbA1c, and the number of teeth was compared between age-groups. DM was defined by an HbA1c ≥6·5%. Findings: Fifty-two-point-seven percent were women and the mean (SD) age was 47·7 (9·6) years. Higher HbA1c was associated with fewer teeth if >30 years of age ( P for trend 30 years of age ( P <0·0001). The relative risks of having <24 teeth were 2·4-fold (95% confidence interval [CI]:2·19–2·67) for diabetic participants, 2·26-fold (95% CI:2·17–2·36) for smokers, and 4·16-fold (95% CI:3·70–4·67) for smokers with DM, compared with non-smokers without DM. Interpretation: Poor glycaemic control is strongly associated with the number of teeth remaining. The impacts of DM and smoking on tooth number were additive in middle age. These data emphasize glycaemic control, cessation of smoking, and the optimisation of oral care for the protection against tooth loss in patients with DM, from a young age. Funding Statement: Sunstar Inc. Declaration of Interests: KH, MI, TY, MH, and AI are employees of Sunstar Inc. HM received research support unrelated to this study from Astellas Pharma Inc., AstraZeneca K.K., Bayer, Daiichi Sankyo, Eli Lilly Japan, Kowa Pharmaceutical, Kyowa Hakko Kirin, Miki Corporation, Mitsubishi Tanabe Pharma, MSD, Nippon Boehringer Ingelheim, Nipro, Nissan Chemical Corporation, Novo Nordisk Pharma, Novartis, Ono Pharmaceutical, Sanofi, Sumitomo Dainippon Pharma, Taisho Toyama Pharmaceutical, Takeda Pharmaceutical, Sanwa Chemical, Shionogi, Teijin Pharma, and lecture fees and fees for serving on advisory boards from AstraZeneca K.K., Daiichi Sankyo, Eli Lilly Japan, Mitsubishi Tanabe Pharma, MSD, Nippon Boehringer Ingelheim, Novo Nordisk Pharma, Sanofi, Sumitomo Dainippon Pharma, Takeda Pharmaceutical. KM received grants from Astellas, AstraZeneca, and Ono Pharmaceutics that were unrelated to this study. No other potential conflicts of interest relevant to this study are declared. Ethics Approval Statement: The authors stated that because the records are publicly available and the data are de-identified, this study was exempt from institutional review approval.