Relationship between periodontal status and diabetes is bidirectional
MedWire News: Periodontal disease increases the risk for diabetes, and diabetes increases the risk for periodontal disease, indicating a bidirectional relationship between the two conditions, Japanese researchers report.
Previous studies have revealed that patients with diabetes experience a significantly greater rate of progression of periodontal disease than patients without diabetes. However, the effect of periodontal disease on the progression of diabetes is less clear.
In the present study, Ichizo Morita (Aichi-Gakuin University, Nagoya) and colleagues performed two case-control studies to determine the association between the 5-year incidence of periodontal disease and glycated hemoglobin (HbA1c) level, and the relationship between periodontal disease and the 5-year incidence of HbA1c levels at or above 6.5%, indicating diabetes.
Participants in the two studies worked in and around Nagoya City and had annual health check-ups between December 1997 and February 2006. Only those individuals who had repeated assessment of periodontal disease or HbA1c at 5 years were included.
For the study determining the effect of HbA1c level on periodontal disease, 5856 individuals without significant periodontal disease (no periodontal pockets ≥4 mm) were enrolled. Of these individuals, 5706 had HbA1c less than 6.5% at baseline. By the follow-up examination, 2068 (35%) of individuals had developed periodontal disease, which was more common in individuals who were male, older, had a higher body mass index (BMI), and who were former or current smokers.
At the 5-year follow up, the relative risk for developing periodontal disease was 1.47 times higher in individuals with an HbA1c level greater than or equal to 6.5% compared with individuals with a level below 6.5%. After adjustment for BMI, smoking status, gender, and age, this risk was reduced to 1.17, but remained statistically significant.
For the study determining the effect of periodontal disease on HbA1c levels, 6125 individuals with an HbA1c level below 6.5% were enrolled. Of these individuals, 5748 had significant periodontal disease at baseline, which was more common in individuals who were male, older, had a higher body mass index (BMI), those who were former or current smokers, and those who had higher alcohol consumption.
At the 5-year follow up, the relative risks for having a HbA1c level greater than or equal to 6.5% were 3.12 for periodontal pockets of 4-5 mm, and 4.85 for periodontal pockets of 6 mm or more compared with individuals without periodontal disease. After adjustment for BMI, alcohol consumption, smoking status, gender, and age these risks were reduced to 2.47 and 3.45, respectively.
Writing in the Journal of Dental Research, Morita and colleagues propose two hypotheses for these results: that periodontal disease increases the systemic inflammation already present in diabetic patients, or that both periodontal disease and diabetes share common risk factors.
The authors conclude that "the risk of developing periodontal disease was associated with levels of HbA1c, and the risk of elevations of the level of HbA1c was associated with having periodontal pockets of more than 4 mm. These findings suggest that the level of HbA1c and progress of periodontal disease have a bi-directional relationship."
By Iain Bartlett