The bi-directional link with diabetes

Have you ever heard of a "reviewaholic" when it comes to researching literature? If there is such a thing, I'm one and so is my good friend, Frank Varon, DDS.

by Lynne H. Slim, RDH, BSDH, MSDH

Have you ever heard of a “reviewaholic” when it comes to researching literature? If there is such a thing, I’m one and so is my good friend, Frank Varon, DDS. Frank and I met several years ago at a Diabetes Translational Conference in Miami. In addition to being a general dentist, Frank has an interest in diabetes care issues that was inspired by his father, an endocrinologist.

Taylor (2001) reported consistent evidence (observational studies) of greater prevalence, severity, extent, or progression of at least one manifestation of periodontal disease in patients with diabetes.1 According to Soskolne and Klinger, the Nutrition Examination Survey (NHANES) III data confirms a significantly high prevalence of periodontitis in individuals with diabetes compared to individuals without diabetes. Prevalence of diabetes in persons with periodontitis is double that of people without periodontitis.2

One of the gray areas in research is the bidirectional relationship between diabetes and periodontal disease. I call it a gray area because the strength of the evidence surrounding the hypothesis that periodontal infection has an adverse, yet modifiable, effect on glycemic control is still being questioned.

Not all studies report an improvement in glycemic control after periodontal treatment.1 The Cochrane oral health group recently reported in 2011 that there is evidence of a small improvement in glycemic control following periodontal therapy, but they also stated that there are few studies available, and individually these studies lack the statistical power to detect a significant effect. The Cochrane authors recommended that larger, carefully conducted, rigorous studies are still needed to confirm the bilateral hypothesis.3

I recently asked Frank some questions about the bidirectional nature of this link, and I included questions that I thought would be of particular interest to the practicing clinician.

1. Can you discuss the strength of the evidence to support the theory of a bidirectional relationship between diabetes and periodontitis

The theory that a bidirectional relationship exists between diabetes and periodontitis is based on numerous dental studies. For the most part, the A1c (the average glucose for the previous two to three months) was monitored prior to periodontal therapy and into the postoperative period. The statement that this relationship exists is based primarily on studies that lasted only two to three months. In those studies that monitored the A1c one or two years after periodontal therapy, the results revealed that the A1c levels, while dipping the first few months, slowly returned to the original prestudy A1c baseline. The reason for this is unknown; however, the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) both reported that after a therapeutic change in diabetes patients, the A1c declined for six to eight months, only to slowly rise back to baseline levels in one to two years if there was no change in regimen.

The relationship between the A1c and diabetes complications took seven to 10 years of medical research to establish. Many dental researchers have attempted to establish the bidirectional relationship between diabetes and periodontitis without considering the strength of the evidence.

2. Nurses and physicians worry about impaired wound healing when a patient’s blood glucose control is poor. Should RDHs be concerned about it too, particularly when performing periodontal debridement? What precautions should they take when they debride/disinfect periodontal pockets in patients with diabetes

Poor glycemic control causes poor white blood cell activity. RDHs should be concerned and screen patients to determine their glycemic status before engaging in periodontal debridement. As for precautions to pocket debridement in diabetes patients, one must be wary that with poor glycemic control comes the potential for cardiovascular incidents while the patient is in the dental chair. In other words, as dental professionals we should be mindful that cardiovascular disease is the leading cause of morbidity and mortality for diabetes patients.

3. What is the probability of undiagnosed diabetes in the dental office, and how can RDHs and dentists screen patients for diabetes

RDHs can be actively involved in screening for diabetes. Recognizing the variety of risk factors associated with undiagnosed diabetes as part of a careful health history review is critical to patient safety and successful treatment. Individuals with a family history of diabetes, hypertension, high cholesterol, obesity, and clinical evidence of periodontal disease should be carefully screened. Extraoral signs include acanthosis nigricans on the neck of the patient. You can view a photo at Also, Mexican men have a high probability of having undiagnosed diabetes.

4. Many years ago, Dr. Harald Löe (periodontal researcher) suggested that periodontitis is the sixth complication of diabetes. What did he mean by this statement and is it true

Löe used panoramic radiographs from members of the Gila River Reservation in Arizona to measure/assess the presence and extent of periodontal disease by measuring the difference in interproximal bone levels between the CEJ and apex of the tooth in patients with a confirmed diagnosis of diabetes mellitus and those without diabetes (control group).

His results showed that there was increased bone loss in patients with diabetes. However, there were similar patterns of bone loss associated in the same areas of the oral cavity (primarily the molars and lower anterior teeth) between both groups, with bone loss being worse in the diabetes group. In addition, if a tooth was missing, a value of 100% was assigned for bone loss, equating this with periodontal disease.

There did not seem to be an allowance for those teeth extracted due to caries. It was a common practice (and still is to this day) to extract a tooth due to deep caries and pulpal involvement.

Dr. Loe’s conclusion that periodontal disease is “the sixth complication of diabetes” is based on his research alone without consultation with governing groups overseeing disease definitions. Currently the World Health Organization and the Expert Committee on the Classification of Diabetes Mellitus are the medical entities assigned to define diabetes mellitus and its complications.

To date these groups have acknowledged that periodontal disease is a diabetes complication, but they have not ruled that it is “the sixth complication of diabetes.” It is imperative that when conducting and reviewing dental research involving medical problems that the researchers abide by the medical entities that provide standardized disease nomenclature.

1. Taylor GW. Bidirectional interrelationships between diabetes and periodontal diseases: An epidemiological perspective. Ann Periodontol 2001; 6: 99−110.
2. Soskolne WA, Klinger A. The relationship between periodontal diseases and diabetes: an overview. Ann Periodontol 2001; 6: 91-98.
3. Simpson TC, Needleman I, Wild SH, et al. (May 12, 2010). Treatment of periodontal disease for glycaemic control in people with diabetes. Retrieved from

Lynne Slim, RDH, BSDH, MSDH, is an award-winning writer who has published extensively in dental/dental hygiene journals. Lynne is the CEO of Perio C Dent, a dental practice management company that specializes in the incorporation of conservative periodontal therapy into the hygiene department of dental practices. Lynne is also the owner and moderator of the periotherapist yahoo group: Lynne speaks on the topic of conservative periodontal therapy and other dental hygiene-related topics. She can be reached at or

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