Background
Diabetes mellitus (DM) and periodontal disease (PD) represent two pathological entities with high prevalence. Several studies suggest a bidirectional relationship between these two diseases. The evaluation of the incidence of PD in a population of patients with DM is determinant to define strategies of prevention and treatment.

Aim
To evaluate the incidence and characteristic of PD in a population of patients with DM

Method
We evaluated 179 consecutive patients followed in the diabetes outpatient clinic of Trás-os-Montes and Alto Douro Hospital Center (CHTMAD), Vila Real, Portugal. The population was evaluated for demographic characteristics, anthropometric parameters, HbA1c, DM complications, comorbidities and pharmacological therapy. Oral health habits were also characterized and an evaluation of the oral cavity was carried out by a team of medical dentists with evaluation of depth of periodontal pockets, gingival recession, and bleeding on probing. The presence and severity of PD was characterized by the CPI (Community Periodontal Index) index: from 0 (healthy periodontal condition) to 4 (deep periodontal pockets). Statistical analysis was performed with t-test and chi-square test. A value of p <0.05 was considered statistically significant.

Results
The population evaluated consisted of 45.8% women, with a mean age of 62.9 ± 12.0 years and a time since the diagnosis of DM of 16.1 ± 9.5 years. 94.4% of the individuals were classified as type 2 DM. Regarding oral health habits, 32.2% of the subjects did not brush daily, 84.3% had <1 medical dentist consultation per year and 35.2% did not had any medical dentist consultation in the last 5 years. 97.3% of the patients had PD (9.4% with CPI classification 1-2 and 87.9% with CPI classification 3-4). The presence of more severe PD (CPI 3-4) was associated with male sex (p = 0.008), lower number of brushings per day (p = 0.006) and poor oral hygiene (p = 0.026). Patients with more severe PD were also shown a tendency to a higher prevalence of diabetic retinopathy (42.4% vs 16.7%, p = 0.088), higher HbA1c (8.21 ± 0.57 vs 7.53 ± 0.30, P = 0.653) and current or past smoking (34.7% vs 16.7%, p = 0.127).

Discussion
We observed a high prevalence of PD in patients followed at the CHTMAD diabetes clinic. The presence of poor oral hygiene habits and the difficulty in accessing oral health care seem to contribute to this high prevalence. Given their frequency, screening and early treatment of PD should be a priority in patients with DM.

Characterization of periodontal disease in a population of patients with diabetes mellitus