Focus on the Bidirectional Correlation between Diabetes and Oral Health - Interpretation of the Latest Clinical Research on World Diabetes Day

World Diabetes Day, observed annually on November 14, underscores the importance of recognizing the bidirectional relationship between diabetes and oral health. A recent clinical study has demonstrated that adult patients with type 2 diabetes who engage in interdental cleaning—using dental floss or interdental brushes—at least three times per week experience longer durations of blood glucose levels within the 24-hour target range and exhibit more stable glycemic control. Furthermore, individuals retaining at least 20 natural teeth demonstrate lower overall blood glucose levels throughout the day. These findings emphasize the critical role of oral health maintenance in diabetes management.

Scientific evidence confirms that periodontal treatment in diabetic patients can reduce glycated hemoglobin (HbA1c) levels, suggesting its potential as a beneficial adjunctive strategy in glycemic control. However, most prior studies have primarily focused on clinical interventions, with limited research examining the impact of daily oral hygiene practices on day-to-day glucose regulation in patients with type 2 diabetes. This new study, conducted through a collaboration between The Sunstar Group of Japan, Clinic Masae Minami, and the Minami Diabetes Clinical Research Center in Fukuoka, aims to investigate the association between oral care behaviors and glucose fluctuations, while exploring whether inflammatory responses may mediate this relationship.

The study enrolled 104 adult patients with type 2 diabetes, all of whom wore continuous glucose monitoring (CGM) devices over a 14-day period. Data collection included clinical assessments, biochemical markers, and behavioral information obtained via questionnaires, medical record reviews, and standard blood and urine tests. Variables analyzed encompassed oral hygiene practices, frequency of dental visits, number of remaining teeth, dietary patterns, physical activity levels, and metabolic indicators. Results indicated that participants performing interdental cleaning at least three times weekly not only maintained glucose levels within the target range for extended periods but also exhibited lower mean 24-hour glucose concentrations, reduced fasting glucose levels, and more stable glycemic variability.

Additionally, participants with 20 or more natural teeth showed improved 24-hour glucose profiles compared to those with fewer teeth. More frequent dental visits and twice-daily toothbrushing were associated with better metabolic and inflammatory markers. These associations remained statistically significant even after adjusting for age and gender. Notably, inflammatory markers did not fully account for the beneficial effects of interdental cleaning on glucose control, suggesting the involvement of additional biological mechanisms or behavioral factors.

According to the International Diabetes Federation, approximately one in nine adults globally—around 590 million people—currently lives with diabetes, nearly half of whom are undiagnosed. Projections indicate that by 2050, one in eight adults (approximately 853 million people) will be affected, representing a 46% increase in total prevalence compared to current levels.

Titled "Oral Hygiene Practices and Glucose Profiles Assessed Through Continuous Glucose Monitoring in Adult Patients With Type 2 Diabetes," the study was published online in the journal *Diabetes Spectrum* on August 28, 2025, and will be featured in an upcoming special issue.