Researchers used chairside HbA1c testing during routine appointments at Guy’s and St Thomas’ NHS Foundation Trust. The test, which delivers results in about six minutes without requiring fasting, measured average blood sugar levels over the previous two to three months.
The study examined 911 patients from the King’s College London Oral, Dental and Craniofacial Biobank. All had a confirmed periodontal diagnosis and had not received treatment in the prior year. Of those who did not report diabetes, 227 showed pre-diabetes range results, and 58 fell into the diabetes range. Even after excluding nine patients who already knew they had pre-diabetes, 276 participants — or 35% — had HbA1c levels of 5.7% or higher; 16% exceeded the NICE threshold of 6.0%.
“The findings suggest that dental visits may offer a valuable opportunity to identify those at risk of diabetes, particularly in older patients, those with higher BMI, and people with gum disease,” said Dr. Giuseppe Mainas, specialist periodontist and research associate at King’s College London.
HbA1c levels increased across gum health categories, rising from patients with healthy gums to those with gingivitis and then periodontitis, and continued to climb from stage I to stage IV of the disease. Senior author Professor Luigi Nibali described the connection as bidirectional.
“The relationship between gum disease and metabolic health is bidirectional since impacts one another, as widely established by previous research,” Nibali said. “The inflammatory process can change the metabolic system, and the metabolic system impacts inflammation further. Gum disease can lead to complications of diabetes, and visa-versa.”
After adjusting for other factors, age showed the strongest link to elevated HbA1c, followed by BMI. Periodontal diagnosis had only a borderline or non-significant association.
The chairside device closely matched venous blood samples in a subset of 100 participants, though it slightly underestimated results at higher levels.
The study, the largest of its kind in the UK to use this method in routine dental care, drew from a well-characterized group but was limited to a cross-sectional analysis in a secondary care setting, where more than 82% of participants had periodontitis. It did not examine cost-effectiveness.
Diabetes UK estimates nearly 1.3 million people in the UK may have undiagnosed type 2 diabetes. In the U.S., an estimated 27.6% of adults 18 and over have undiagnosed diabetes, representing about 11 million people, according to the Centers for Disease Control and Prevention.
The researchers said dental appointments could serve as an additional point to spot at-risk individuals and prompt follow-up with a general practitioner.
The findings are published in the Journal of Dentistry.
