A major new study of over 180,000 individuals has shown a significant link between tooth loss and glycemic control in people with diabetes. Those with diabetes with HbA1c ≥ 7.0% had greater tooth loss, even with dental care, compared to those without diabetes or with well-controlled diabetes.

The joint research by Shiga University of Medical Science and international oral healthcare company, Sunstar, also found that individuals with diabetes who only underwent dental treatment (without preventative care) experienced more rapid tooth loss with age.

The cross-sectional research, published in Diabetology International, analyzed a comprehensive medical database of over 700,000 individuals to examine the relationship between dental maintenance, diabetes status, and the number of natural teeth. It found that:

High HbA1c levels ≥7.0% in people with diabetes lost more teeth, even with regular dental care. Findings show the importance of integrated dental and medical care

This study consisted of 705,542 individuals aged 20-74 who underwent annual health check-ups and analyzed their actual dental visits by classifying them into ‘maintenance only’, ‘maintenance and treatment’, ‘treatment only’, and ‘no dental visits’. Diabetes status was determined through diagnosis codes and HbA1c values, with an HbA1c of ≥7.0% indicating above-target glycemic management levels. A subset of 185,820 people aged 40-69 was assessed on tooth number and diabetes status, in the context of their dental maintenance practices, which include regular professional cleanings and check-ups to prevent dental diseases.

Individuals with diabetes are known to be at higher risk of tooth loss and are advised to undergo regular dental care. However, few large-scale studies have previously examined these associations using actual medical claims data and health check-up results to assess the relationship between diabetes and tooth loss.

In this Article

Key findings

Dental visit trends

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Only 46% of participants visited a dentist during the year, with rates particularly low among younger individuals (34% in their 20s, 43% in their 30s). Maintenance only visits were just 7% in those in their 20s and particularly low in those with diabetes withHbA1c ≥ 7.0%, who also had a significantly lower rate of maintenance care (Figure 1).

Figure 1 percentage of dental visits by age

Tooth number and glycemic management

The study found that individuals with diabetes with HbA1c ≥ 7.0% had significantly fewer teeth, regardless of whether they received maintenance or treatment-only care. In particular, individuals with diabetes coupled with high HbA1c who only underwent dental treatment experienced more tooth loss with age, suggesting HbA1c management helps preserve teeth.

Figures 2 and 3 The association of age with number of natural teeth, with curves representing model predictions (95% confidence intervals)

While regular dental maintenance was linked with preserving natural teeth, the researchers found no major difference in tooth number between individuals without diabetes and those with diabetes and HbA1c<7.0%, indicating the critical role of blood glucose management in preserving oral health. The findings call for an integrated healthcare approach, with medics and dentists collaborating to support the overall health of patients, with preventive care not just treatment, playing a crucial role, especially in those living with diabetes.

Dr. Katsutaro Morino, Visiting Associate Professor, Shiga University of Medical Science Associate Professor, Kagoshima University Graduate School of Medical and Dental Sciences, comments on the research: “While this is a cross-sectional study and does not establish causality, its strength lies in the scale and detail of the data. These findings reaffirm the importance of regular dental maintenance, particularly for individuals with diabetes. We hope younger generations in particular will take this message to heart.”

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References

Miki Ishikawa, Takako Yasuda, Natsuki Nara, Itsuko Miyazawa, Nakao Takase, Kayo Harada, Atsushi Ishikado, Katsutaro Morino. Association among the number of natural teeth, dental maintenance visits and diabetes status: a cross-sectional study using employment-based healthcare claims database. Journal: Diabetology International, 16; 2 (2025) DOI: https://doi.org/10.1007/s13340-025-00805-1