Hyperglycemia, or high blood glucose levels, is a hallmark of diabetes and can lead to a host of teeth and gum problems. In a vicious cycle, poor oral health can also make it harder to manage diabetes. Wenche S. Borgnakke, DDS, MPH, PhD, explains why it’s imperative for health care professionals to attend to the oral health of their patients with diabetes.

Q: How common are tooth- and gum-related diseases?

A: Gingivitis, a reversible inflammation of the gums, is almost ubiquitous. Up to 90% of any population in the world has inflamed gums. Periodontitis—an irreversible, chronic destruction of both the soft gums and the jawbone around the teeth that causes the gums to shrink and teeth to loosen and eventually fall out—varies across populations. More than 42% of U.S. adults ages 30 years or older with natural teeth have periodontitis, according to an analysis of data from the National Health and Nutrition Examination Survey (NHANES). Its prevalence increases with age and is greater in certain subgroups, such as current smokers.

Q:  Why is poor oral health a concern for people with diabetes?

A: People with diabetes have a 34% elevated risk of periodontitis and a 50%–100% greater risk of losing teeth compared to people with blood glucose levels in the healthy range. Many people with diabetes are edentulous, meaning they have no teeth. Yet people with diabetes need all the teeth they possibly can keep and in good working order. Because with aching teeth, or without teeth—or without dentures, which not everyone can afford—people with diabetes are simply not able to follow the nutrition directions from their health care professionals.

Tooth- and gum-related diseases also increase risk for microvascular and macrovascular diabetes complications and death in the presence of periodontitis. People with diabetes who have periodontitis also are at greater risk for retinopathy, neuropathy, kidney disease, and cardiovascular complications compared to people with diabetes who do not have periodontitis.

Among people with diabetes, poor oral health is so common that oral health really should be included as part of managing diabetes. Diabetes in America, 3rd Edition, includes a chapter on oral health, as does the 2019 edition of the International Diabetes Federation’s Diabetes Atlas (PDF, 20.8 MB) . This is a great testament to the fact that the medical diabetes community is beginning to recognize the importance of oral health in managing diabetes.

Q: How does diabetes affect oral health, and vice versa?

A: Hyperglycemia (diabetes) and periodontal disease mutually and adversely affect each other.

There is a large body of evidence for hyperglycemia leading to gum disease. Importantly, it is the level of hyperglycemia, not simply the diagnosis of diabetes, that determines the extent of impact on oral tissues. People with uncontrolled diabetes have weakened immune systems, which can lead to chronic inflammation in the soft and hard bone tissues around the teeth. This can make it much harder to heal after surgery in the mouth or a tooth extraction, compared to people with blood glucose levels in the healthy range. Hyperglycemia also can lead to cavities, the need for root canal treatment, failing dental implants, thrush (a yeast infection in the mouth), oral cancer, dry mouth, burning mouth, tooth loss, and other problems.

There is less research on how gum disease contributes to diabetes. In the first systematic review on the potential effect of periodontal infection on blood glucose levels, the limited data show that having chronic periodontitis leads to elevated glucose levels, which in turn contributes to type 2 diabetes and gestational diabetes, poor glucose control in already existing type 2 diabetes, and further diabetes complications.

Q: Can oral health care improve blood glucose levels?

A: Studies reveal that periodontal treatment (“deep cleaning”) at a general dental office can decrease blood glucose levels in type 2 diabetes in 3 to 4 months by nearly the same level as adding a second oral anti-diabetic medication to metformin (see here, here, and here). So, this is a relatively simple way to decrease and control blood glucose levels.

Yet many studies have shown that people with diabetes do not go to the dentist as often as those without diabetes. You can speculate on the reasons. It could be that they are so burdened down with all their disease care that they neglect their dental care. Another explanation is that type 2 diabetes is very much a socioeconomic disease. Some people with type 2 diabetes have low socioeconomic status and health literacy. They have many other problems that completely overshadow anything like going to the dentist.

Q: Conversely, can diabetes care contribute to oral health?

A: Unfortunately, there is minimal research on how improved glycemic control affects teeth and periodontal tissues. One study of just 35 people with type 2 diabetes found that improved blood glucose control reduced bleeding in the gums, but there was no effect on periodontal pocket depth—the vertical space between the tooth and the gum, usually regarded as diseased when 4mm or deeper. Medical researchers conducting diabetes studies are not routinely including measures inside the mouth when they record other baseline measures. Yet this kind of research absolutely needs to be done.

Q: What can health care professionals do to improve the oral health of their patients with diabetes?

A: Be aware of the importance of oral health, know what to look for, and refer patients to dentists when you see issues. Some issues to look for include

• specific signs of infection in the mouth, such as swelling, reddening, pus, and foul smell (bad breath)
• signs of cavities or broken and loose teeth
• any trouble with the mouth, such as trouble biting off, chewing, or swallowing

We all need to work together—dentists, physicians, nurses, nurse practitioners, pharmacists, sociologists, physical therapists, diabetes educators, and social workers—to be centered on the health of the patient. Needless to say, the patient also needs to take part in this collaboration.

Q: What information on oral hygiene can health care professionals share with their patients with diabetes?

A: It’s important to educate patients about the importance of good oral health, especially keeping as many teeth as possible—not only for managing their diabetes but also to preserve their quality of life.

• Explain to your patients that by taking care of their teeth and gums, they are keeping down inflammation, which automatically decreases their blood glucose level.
• Encourage your patients to brush their teeth—after breakfast and just before going to sleep at night—with a super-soft toothbrush and fluoride toothpaste, using very small movements while ensuring the tip of the bristles reach into the space between the tooth and the gums. They can use dental floss if they take care to floss correctly without damaging their gums.
• Emphasize to patients that they should have a professional dental exam at least once a year, because periodontitis can be completely silent. Patients may not even know they have it until a tooth gets loose. They should get professional deep cleaning—scaling and root planing—if they have periodontitis and the pockets are deeper than they can clean with their toothbrush. This may be necessary only once.

You can help patients obtain affordable dental care through the network of “safety net” clinics. Some Federally Qualified Health Centers include dental clinics that provide care on a sliding scale. Dental schools offer care at reduced costs, and state dental organizations also may be able to make referrals for low- or no-cost dental care.

Q: What resources are available to help health care professionals better understand their role in the oral health of their patients with diabetes?

A: In a recently published article, Diabetes and Oral Health: Summary of Current Scientific Evidence for Why Transdisciplinary Collaboration Is Needed, I include in the appendix “Guidelines for Medical & Dental Professionals and Their Patients.” These guidelines can be useful to practitioners in general practice and in medical specialties such as dentistry, diabetes/endocrinology, and cardiology.

The appendix also contains a list of questions patients may ask about their teeth and gums and answers that health care professionals can provide; guidelines for oral health professionals who have patients with diabetes; and a handout on oral health for patients. Separately, I have also created a one-page plain-language handout for patients, “Gum Disease Can Raise Your Blood Sugar Level (PDF, 245 KB) ."