Diabetes Mellitus: Oral Health Complications and Dental Treatment Considerations

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In 2021, the International Diabetes Federation estimated that 537 million people are living with diabetes, and another 541 million people have impaired glucose tolerance.1 The pathophysiology of the disease is a malfunction of the feedback loops between insulin action and insulin secretion.2

Staying abreast of the oral-systemic link associated with diabetes mellitus can be overwhelming. In this article, I hope to present updated information explaining oral diseases that are linked to diabetes mellitus (DM).

Caries Risk

A clear association exists between increased decayed, missing, and filled permanent teeth (DMFT) index and diabetes status. Individuals with DM have an increased risk of developing caries. The association between DM and increased caries risk appears to be multifactorial.3

One factor is the increased level of glucose found in the saliva of patients with uncontrolled DM. Saliva mirrors plasma; if there is a high glucose level in plasma, there will be a higher glucose level in saliva. The increased glucose level in saliva creates a more acidic environment conducive to dental caries.3,4

Additionally, individuals with DM have higher S. mutans counts than those without DM. As you can imagine, this increases their risk of developing dental caries. Studies have found a higher count of S. mutans led to three times more carious lesions developing in individuals with uncontrolled DM than in control groups.3

Preventive measures that can be taken for patients with DM include professionally applied fluoride varnish, an increase in the frequency of recare appointments, prescription fluoride toothpaste, and nutritional counseling. Though it is unclear if patients with controlled diabetes are at an increased risk of caries, these preventative measures are conservative and would be appropriate to recommend to all patients with DM.3,4

Periodontal Risk

Periodontal disease is often a co-morbidity for DM. This has been well established as they have a bidirectional relationship. Treatment for periodontal disease reduces HbA1C and recently has been determined to reduce health care costs for patients with DM, excluding pharmacy costs.5,6

Many studies have investigated the link between periodontal disease and DM. Though multiple pathways are indicated in the bidirectional relationship, an interesting finding in a recent study discovered there was less of a shift in the oral microbiome of patients with DM and periodontal disease compared to individuals without diabetes yet with periodontal disease.7

This finding indicates that patients with diabetes have a poorer immune response requiring less dysbiosis to initiate periodontal disease than nondiabetic individuals. Due to this decreased tolerance of periodontal pathogens, emphasis on biofilm control is prudent in individuals with DM to prevent any shift that could initiate periodontal disease or contribute to the progression of periodontal disease in individuals with DM.7

Preventive measures should include more frequent recare appointments for patients with DM, even with the absence of periodontal disease. The six-month frequency for recare appointments is not something that should be written in stone. Determining each patient’s individual needs will help manage and prevent disease onset and progression.

Oral Cancer Risk

A recently published systematic review and meta-analysis found that individuals with DM have a significantly higher risk of developing oral cancer when compared to the prevalence in the general population. Further, it was determined that death from oral cancer in individuals with DM was two times higher than in the general population. This was found for other cancers as well, including liver, pancreatic, ovarian, colon, lung, bladder, and breast.8

The mechanism by which oral cancer and DM are associated has been postulated to be the activation of the CCND1 oncogene and the upregulation of its protein (cyclin D1). This oncogene and its protein have been identified as a key player in oral cancer’s pathogenesis through increased proliferation and favoring the migration capacity of malignant cells.8

Insulin resistance activates receptors which then activate pro-proliferation and antiapoptotic pathways that support the onset and proliferation of cancer cells. The main pathway activated by insulin resistance leads to the activation of the CCND1 oncogene. Additional considerations are that hyperglycemia causes oxidative stress with free radicals that damage DNA. Tumor cells also feed on increased glucose, a well-established hallmark of cancer, further supporting the connection between cancer and DM.8

Dental hygienists should never skip oral cancer screening. However, it is even more important to take time to thoroughly examine patients with DM for any changes in tissue appearance or texture. DM patients with tissue changes that do not resolve in two weeks should be sent for a biopsy to ensure the lesion is benign, as early diagnosis is key to better treatment outcomes in oral cancer. No matter how inconspicuous a lesion appears, a biopsy is the only definitive way to rule out oral cancer.

Oral Lichen Planus

There is a moderate association between oral lichen planus (OLP) and DM. There is a stronger association between people of European descent. The lowest association is among people of Asian descent. It is more commonly seen in adult populations with DM and almost nonexistent in adolescents with DM, which is well-established regarding OLP in the general population.9,10

Though a clear biologic mechanism is unknown, both DM and OLP are inflammatory conditions. OLP is immune-mediated, as is type 1 DM. However, type 2 DM is not defined as “immune-mediated” but rather considered strictly an inflammatory disease associated with lifestyle and genetics. Nonetheless, the inflammatory process may be the key factor in the association between OLP and DM. Further research is needed to clearly define the biologic mechanism.9-11

There are no preventive measures that can be taken to prevent the onset of OLP. However, understanding the association between OLP and DM may help with proper diagnosis and early treatment to manage symptoms.10

Other Oral Complications

In addition to the above-mentioned complications, individuals with DM also suffer an increased risk of oral candidiasis, xerostomia, delayed wound healing, burning mouth syndrome, and geographic tongue.12

An estimated 25% of diabetic patients experience oral candidiasis infections. It is more common among patients with uncontrolled DM. The increased salivary glucose, as well as immune dysfunction and acid production, promotes the growth of oral candidiasis.12

Xerostomia affects an estimated 46% of individuals with DM. Though salivary glucose levels are higher in patients with DM, decreased salivary flow is even more detrimental to oral health. In addition to increasing the risk of caries, xerostomia also affects the patient’s quality of life and compromises nutritional intake, speech, and the ability to tolerate dental appliances.12

Individuals with DM can also suffer from peripheral diabetic neuropathy. These individuals have an increased risk of experiencing burning in the oral tissues. Burning mouth syndrome in patients with DM is thought to be associated with a neuropathic origin. Geographic tongue is an inflammatory disease associated with DM, though not considered neuropathic origin, like burning mouth syndrome.12

Delayed healing is also a complication to consider in the dental setting. Extractions, implants, and even non-surgical periodontal therapy require proper healing to be successful. Though non-surgical periodontal therapy may improve the management of DM, extractions and implants should be postponed if possible until the patient’s DM is well managed. Patients with well-managed DM are not at an increased risk for delayed healing. Treatments such as extractions and implant placement can be done without concern for delayed healing associated with DM.12


When reviewing medical history, take the time to note if the patient has DM. This step may help you better understand any oral complications and provide guidance for treatment planning and recommendations for preventive measures. It is prudent to note the patient’s most recent HbA1C in their clinical notes. An elevated HbA1C would warrant postponing implant surgeries until the patient’s DM is better managed. Implant failures are associated with uncontrolled DM.

Many patients with DM require different care than those without DM, which should be acknowledged and addressed at each appointment. Being complacent with medical history reviews and information gathering, such as current HbA1C, will not serve patients and manage their oral health in the way in which they deserve.

Take the time to discuss the patient’s systemic health as it affects their oral health. It would be beneficial to have an extended appointment for patients with DM to reduce time constraints. Oral health literacy is abysmal, and many patients are unaware of the connection between their systemic and oral health. We must not assume that patients know or understand the complexities of the oral-systemic link. Improving the patient’s oral health literacy may also lead to better oral health for a lifetime.

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  1. Magliano, D.J., Boyko, E.J. (2021). IDF Diabetes Atlas (10th ed.). International Diabetes Federation. https://www.ncbi.nlm.nih.gov/books/NBK581934/
  2. Galicia-Garcia, U., Benito-Vicente, A., Jebari, S., et al. Pathophysiology of Type 2 Diabetes Mellitus.International Journal of Molecular Sciences. 2020;21(17): 6275. https://doi.org/10.3390/ijms21176275
  3. Latti, B.R., Kalburge, J.V., Birajdar, S.B., Latti, R.G. Evaluation of Relationship between Dental Caries, Diabetes Mellitus and Oral Microbiota in Diabetics.Journal of Oral and Maxillofacial Pathology. 2018;22(2): 282. https://doi.org/10.4103/jomfp.JOMFP_163_16
  4. Sabharwal, A., Ganley, K., Miecznikowski, J.C., et al. The Salivary Microbiome of Diabetic and Non-diabetic Adults with Periodontal Disease.Journal of Periodontology. 2019;90(1): 26-34. https://doi.org/10.1002/JPER.18-0167
  5. Thakkar-Samtani, M., Heaton, L.J., Kelly, A.L., et al. Periodontal Treatment Associated with Decreased Diabetes Mellitus-related Treatment Costs: An Analysis of Dental and Medical Claims Data.Journal of the American Dental Association. 2023;154(4): 283-292.E1. https://doi.org/10.1016/j.adaj.2022.12.011
  6. Bui, F.Q., Almeida-da-Silva, C.L.C., Huynh, B., et al. Association between Periodontal Pathogens and Systemic Disease.Biomedical Journal. 2019;42(1): 27-35. https://doi.org/10.1016/j.bj.2018.12.001
  7. Shi, B., Lux, R., Klokkevold, P., et al. The Subgingival Microbiome Associated with Periodontitis in Type 2 Diabetes Mellitus.The ISME Journal. 2020;14(2): 519-530. https://doi.org/10.1038/s41396-019-0544-3
  8. Ramos-Garcia, P., Roca-Rodriguez, M.D.M., Aguilar-Diosdado, M., Gonzalez-Moles, M.A. Diabetes Mellitus and Oral Cancer/Oral Potentially Malignant Disorders: A Systematic Review and Meta-analysis.Oral Diseases. 2021;27(3): 404-421. https://doi.org/10.1111/odi.13289
  9. Mallah, N., Ignacio Varela-Centelles, P., Seoane-Romero, J., Takkouche, B. Diabetes Mellitus and Oral Lichen Planus: A Systematic Review and Meta-analysis.Oral Diseases. 2022;28(8): 2100-2109. https://doi.org/10.1111/odi.13927
  10. Hamour, A.F., Klieb, H., Eskander, A. Oral Lichen Planus. Canadian Medical Association journal. 2020; 192(31): E892. https://doi.org/10.1503/cmaj.200309
  11. Sapra, A., Bhandari, P. Diabetes Mellitus. (2022, June 26). StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK551501/
  12. Nazir, M.A., AlGhamdi, L., AlKadi, M., et al. The Burden of Diabetes, Its Oral Complications and Their Prevention and Management. Open Access Macedonian Journal of Medical Sciences. 2018; 6(8): 1545-1553. https://www.researchgate.net/publication/327871304_Burden_of_diabetes_its_oral_complications_and_their_prevention_and_management