Association between periodontitis and glycosylated haemoglobin before diabetes onset: a cross-sectional study

Objectives: The aim of the present cross-sectional study was to investigate the association between serum glycosylated haemoglobin (HbA1c) levels and periodontal status in patients with periodontitis (CP) and periodontally healthy controls. Furthermore, the objectives were to determine if the periodontitis influenced the serum HbA1c levels. Materials and methods: A total of 93 patients with CP and 95 periodontally healthy subjects were enrolled in the present study using a cross-sectional design. At baseline, patients were examined and characterized on a regular basis for blood serum parameters and non-fasting blood samples levels. In all patients, a full periodontal examination was performed and clinical attachment loss (CAL) was the primary outcome variable chosen. The spearman correlation, a stepwise multivariable linear regression, and Jonckheere-Terpstra tests were applied in order to assess the relationship between HbA1c levels and periodontitis. Results: Patients in the CP group presented a significantly higher median serum level of HbA1c [40.9 (31.2; 45.6) mmol/mol)] compared to patients in the healthy control group [35.3 (29.6; 38.6) mmol/mol)] (p < 0.001). HbA1c levels were negatively correlated with the number of teeth and positively correlated with C-reactive protein levels and all periodontal parameters (p < 0.001). Moreover, there was a significant decrease in the number of teeth when HbA1c levels increased (P-trend < 0.001), while there was a significant increase in periodontal parameters (CAL, p = 0.002); PD, p = 0.008; BOP, p < 0.001) when levels of HbA1c increased. Conclusions: Patients with CP and undiagnosed diabetes presented significantly higher serum levels of HbA1c compared to periodontally healthy controls. Moreover, the presence of periodontitis was positively correlated with serum HbA1c levels before diabetes onset. Clinical relevance: HbA1c levels were positively correlated with the severity of periodontitis before diabetes onset.