Medical Matters: Blood-sugar blues – how dentists can help diagnose diabetes

You are sitting in the dentist’s chair when out of the blue she says, “I think we should check you for diabetes.” Anticipating a referral to your GP, you are somewhat taken aback when she offers to screen for the disease there and then.

This scenario may be closer to reality than we think. Writing in the current issue of the Journal of the Irish Dental Association, Dr Denise MacCarthy and colleagues from the Dublin Dental University Hospital suggest that screening people at high risk of diabetes in the dentist's surgery is cost effective. So what might be going on in our mouths to make a dental check-up for diabetes a reality?

Apart from the more obvious signs and symptoms of high blood-sugar such as sudden, unexplained weight loss, polyuria (increased urination), polydipsia (increased thirst) and lethargy, there are various oral features that can be detected during a routine dental examination that might suggest undiagnosed diabetes.

Oral signs

The most common oral signs of diabetes are gingivitis (gum disease) and periodontal disease. Adults are three times more likely to have periodontitis if they suffer from diabetes. Initially, people with diabetes develop gingivitis; the transition to periodontitis is related to the rate at which sugar control worsens.

Excessively passing urine leads to dehydration, which in turn causes a reduced production of saliva. This and an altered salivary consistency leads to a dry mouth and a diminished sense of taste.

Oral thrush is another feature – the fungus Candida albicans often lives quietly in our mouths but in someone with diabetes it flares out of control due to a combination of high sugar in the saliva and impaired function of one of the sub-types of white blood cell.

An unpleasant burning sensation in your mouth may be a sign of chronically elevated blood sugar. This has been linked to nerve damage, one of the complications of long-standing diabetes. And recurrent mouth ulcers, frequent herpes infections and serial dental abscesses are other signs that signal the possibility of diabetes to a dentist.

Of course looking for a random series of clinical signs does not, on its own, constitute a formal screening process. Some form of standardised test, which is reliable, relatively inexpensive and reproducible is needed.

It turns out that glucose levels in blood obtained from the gingival crevice compare well with glucose levels of blood obtained from a finger puncture or from venous blood.

Glucose measurement

A relatively small amount of blood is all that is required, with research showing that about 85 per cent of us are capable of providing enough blood for a successful glucose measurement.

According to the authors, obtaining a blood sample from the gum involves isolating a suitable tooth with a cotton roll, probing the pockets around the tooth with light pressure and then placing a test strip directly into contact with the gingival crevicular blood. This is then placed into a portable machine, with a reading usually available in five seconds.

I must say this sounds less painful than a needle-stick. There is also an argument that dentists have a high annual patient attendance, which facilitates screening. And, of course, they may be more familiar with the mouth and its pathology than us medics.

MacCarthy and her colleagues suggest a four-step screening process: 1. Classify high-risk patients according to American Diabetes Association criteria. 2. Look for the presence of periodontal disease. 3. Look for the presence of oral features of undiagnosed diabetes. 4. Carry out a chair-side point-of-care gingival crevicular blood test measuring the diabetes marker HbA1c.

“Pending further research focused on trailing the above proposed screening model and pending approval from medical and dental councils, it is suggested that a universal clinical guideline to screen patients at dental visits for undiagnosed diabetes mellitus be developed, implemented and made a public health priority,” they conclude.

mhouston@irishtimes.com muirishouston.com