Best Practices for Managing the Diabetic Patient in the Dental Office

According to the most recent (2014) National Diabetes Statistics Report of the Centers for Disease Control and Prevention, some 29.¹ million Americans currently have diabetes, including both type 1 and type 2.¹ This constitutes 9.3% of the total US population, with an additional 86 million Americans identified as having prediabetes. Both the incidence and prevalence of diabetes have been steadily increasing.²

A chronic inflammatory disorder, diabetes is associated with significant morbidity and mortality and is a leading cause of kidney failure, blindness, limb amputation, myocardial infarction, and stroke. It also is now understood to have a two-way relationship with periodontal disease, with poor glycemic control adversely affecting the periodontium, and inflammatory periodontal diseases associated with potential negative effects on glycemic control.³ Given the growing number of diabetic patients (Table 1) and the close association between diabetes and periodontal disease, it is incumbent on oral healthcare practitioners to be aware of the best practices for treating this population. The aim of this article is to review some of these practices.

Some understanding of the relationship between diabetes and periodontal disease dates back more than 100 years, to before the discovery of insulin. Clinicians observed that patients with poorly controlled diabetes also often had severe periodontal disease; the outmoded term “diabetic periodontopathy” attests to this association. Over time, awareness grew that flare-ups in diabetic patients’ periodontal disease made control of their blood sugar more difficult, or “brittle.”²

Epidemiological studies, particularly those focusing on the Pima of Arizona, a Native American tribe that has the highest prevalence of diabetes anywhere, helped to document the bidirectionality of the association between diabetes and periodontal disease. Over the past 30 years, understanding of the biological mechanisms underpinning this association also has grown exponentially.

A major breakthrough has been the understanding that patients with diabetes have an altered immunoinflammatory response to challenges by microorganisms. In general, the neutrophils of such individuals tend to be hypofunctional, while conversely, their monocyte and macrophage cell lines tend to be hyperresponsive.^2,4 The result is a decrease in the nonspecific killing of bacteria and an increase in the production of pro-inflammatory cytokines that may result in destruction of host tissue.

In diabetic patients with poor glycemic control, bacterial antigens tend to trigger more tissue inflammation than they would in nondiabetic patients, and that inflammation is responsible for most of the periodontal destruction around the tooth. Conversely, there is also a systemic inflammatory component, ie, some of the inflammatory cytokines spill over into the blood and interfere with the insulin receptors’ ability to work well. They thus contribute to insulin resistance.

As these and other insights into the biological mechanisms associated with diabetes have accumulated, the medical management of diabetes has also undergone tremendous change, driven in large measure by research published in the 1990s about the impact of improved glycemic control on diabetic complications. The landmark 1993 Diabetes Control and Complications Trial demonstrated that changing from conventional insulin treatment regimens to more frequent injection and more intensely monitored therapy improved glycemic control and dramatically reduced the risk for diabetes-induced disease of the eye, kidney, and nerves.⁵ In 1998 the United Kingdom Prospective Diabetes Study also showed a marked reduction in complications when patients newly diagnosed with type 2 diabetes were treated intensively.⁶

As a result, type 1 patients today typically use an insulin pump, or they take three or four injections of short-acting insulin each day plus a long-acting (basal) insulin. Patients with type 2 diabetes often take multiple oral medications, often in combination with insulin injections. Besides reducing the risk for major complications, improving the glycemic control for such patients appears to be associated with a decreased risk and/or severity of periodontal diseases and may enable a more favorable response to treatment of periodontal disease. On the other hand, the more intensive regimens that have become the norm for contemporary diabetic patients pose some additional challenges for dentists.

Identifying the Diabetic Patient

In order to optimally treat diabetic patients, the first challenge for dentists is to identify those individuals who have diabetes. The most obvious way to accomplish this is to ask patients about their health status. Those who say that they have received a diabetes diagnosis should be asked which type they have. However, a negative response cannot be considered conclusive. The CDC reports that 27.8% of Americans with diabetes are undiagnosed, ie, more than 8 million diabetic Americans are unaware of their condition.¹

Additional questions on the medical history form may help to alert dental office personnel to undiagnosed diabetes. These should include asking if patients have recently been tested for diabetes, if they have a first-degree relative with diabetes, how often they get up in the night to urinate, how much water they drink daily, and how quickly they become hungry again after being fully satiated (polyuria, polydipsia, and polyphagia being well-recognized symptoms). Female patients who have children should be asked if they ever developed gestational diabetes while pregnant, a significant risk factor.

As inexpensive and reliable glucometers have become available, it has been suggested that in-office finger-prick testing of glycated hemoglobin should be offered routinely to all dental patients. One consideration, however, is that the Clinical Laboratory Improvement Amendments (CLIA) of 1988 and their subsequent amended provisions state that although use of an office glucometer is a CLIA-exempt procedure, any office doing such testing is still considered to be a CLIA-waived medical laboratory and must register with the federal government and receive a registration certificate.⁷

A more substantial consideration regarding the use of an in-office glucometer to identify undiagnosed diabetes is the importance of properly interpreting the test results. For example, a markedly elevated glucometer reading in a patient who has not eaten recently may be excellent grounds for urging the patient to see a physician for further testing. A normal fasting plasma glucose level is <100 mg/dl, and a normal 2-hour post-prandial glucose level is <140 mg/dl.⁸ So a patient with a glucometer reading higher than these values may benefit from referral to a physician. It is often more difficult for the dentist to determine what to do when a patient has a glucometer reading that is only slightly elevated or is normal. A normal glucometer reading frequently does not indicate the absence of diabetes, because many people with undiagnosed diabetes have normal blood sugar values at some point in the day, depending on when and what they last ate and how recently they exercised. Informing a patient that he or she does not have diabetes, based on a “normal” single-point-in-time glucometer test result, could potentially expose the practice to substantial liability.

Assessing the Diabetic Patient’s Glycemic Control

Once the oral healthcare practice knows that a given patient has diabetes, the need for information about his or her glycemic status does not stop.⁹ The next important question is: how well is the person’s blood sugar controlled? Optimally, the patient’s physician should be contacted and asked to provide the last 2 years of results of hemoglobin A1c (HbA1c) testing, the test that measures glycohemoglobin levels and provides an estimate of the average blood glucose level over the 30 to 90 days prior to collection of a blood sample.^2,8 The physician should also be asked for a list of the patient’s current medications.

On average, patients whose HbA1c values consistently fall within the recommended range (<7%) have no more risk of developing gingivitis than nondiabetic individuals, with the same level of plaque.^2,9 Conversely, poorly controlled diabetic patients have significantly increased gingival inflammation compared to either well-controlled diabetic or nondiabetic individuals.^10,11 A number of other oral conditions have been believed to be pathognomonic for diabetes. However, this has not been definitively established. Diabetic patients may develop xerostomia as a result of the medications they are taking for related or unrelated systemic conditions. The effect of diabetes on the dental caries rate is similarly unclear. While some studies have demonstrated an increased rate,¹² others have shown similar or decreased rates.^13,14 The fact that many diabetic patients limit their intake of fermentable carbohydrates may reduce the incidence of caries. Other research suggests that people with diabetes as a group are similar to nondiabetic individuals in regard to salivary flow rates, organic constituents of saliva, salivary counts of acidogenic bacteria, salivary counts of fungal organisms, and coronal and root caries rates.^15,16

Treating the Diabetic Patient

The question of what impact treatment for periodontal disease has on glycemic control was first addressed more than 50 years ago. When children with type 1 diabetes were treated for periodontal disease and their insulin requirements were monitored, decreased inflammation in the oral cavity appeared to be associated with improved glycemic control and a reduced need for insulin.¹⁷ Since then dozens of studies have examined the same question; however, results have been mixed.² Engebretson et al in 2013 reported that periodontal therapy did not measurably impact glycemic control in several hundred diabetic patients with relatively good glycemic control.18 However, several systematic reviews of smaller studies have found the opposite results.^19,20

Closer scrutiny of the research suggests that the apparent contradictions may spring from comparison of different levels of treatment. More comprehensive periodontal treatment regimes in which scaling and root planing is combined with the extraction of severely periodontally involved teeth are more commonly associated with significant reductions in blood sugar levels. The greater the reduction in the bioburden and subsequent reduction in inflammation, the greater the potential for improved glycemic control. Frequent follow-up for cleaning, re-examination, and thorough retreatment for any disease recurrence is likewise recommended.

Another aspect of treating the diabetic dental patient that deserves attention is the risk of diabetic patients developing hypoglycemia while undergoing treatment. Ironically, as diabetic patients have generally achieved increasingly better glycemic control over the past 20 years, decreasing their risk of long-term diabetic complications, the risk for hypoglycemia has increased. In the 1993 Diabetes Control and Complications Trial, patients who received intensive insulin therapy had a three times greater incidence of severe hypoglycemia, often resulting in seizures and loss of consciousness, than the controls who received conventional therapy (one or two daily insulin injections, rather than three or more). Moreover, 36% of the severe hypoglycemic reactions occurred without any warning symptoms. (In 51% of the reactions, patients failed to recognize warning symptoms that did occur.) Close attention to the signs and symptoms of hypoglycemia, along with ways to avoid its occurrence, is imperative.

One way to assess a patient’s risk for hypoglycemia is to consider how well they have been controlling their blood sugar levels in the recent past, as evidenced by HbA1c levels, either self-reported or, preferably, documented by their medical records. In general, the lower the HbA1c, the greater the risk for hypoglycemia, whereas those individuals with consistently elevated HbA1c values (>8%) have a lower hypoglycemia risk. However, some patients with poor glycemic control have HbA1c values that fluctuate considerably over time and may have elevated risk of hypoglycemia at certain times, eg, during periods when glycemic control is better.

An additional way for clinicians to assess the risk of any patient having an acute hypoglycemic event is to determine the patient’s glucose level using a finger-stick glucometer test immediately before treatment. Even if the dental practice lacks its own in-house glucometer, most diabetic patients today possess one, and they should be instructed to bring their glucometers with them to each dental appointment as a matter of routine.

Before treatment, each diabetic patient should be directed to check his or her blood sugar level using the personal glucometer. The result should be documented in the patient’s chart, and, if necessary, appropriate action should be taken. In people without diabetes, symptoms of hypoglycemia usually do not appear until the glucose level decreases to less than 60 mg/dl.²¹ However, hypoglycemia symptoms may appear in diabetic patients at levels higher than that. In general, assuming diabetic patients have taken their normal medications and eaten their usual diet, a good rule of thumb is that if a patient is about to undergo a short (less than 1 hour) procedure, and the glucose level is about 100 mg/dl, treatment can proceed without intervention. However, if the procedure is expected to last several hours and the pretreatment test result is less than 100 mg/dl, the patient should be given a small amount of oral carbohydrate to help raise the blood glucose. Four ounces of fruit juice, for example, will typically increase glucose levels by 30 mg/dl to 40 mg/dl or more, and will thus help prevent the onset of hypoglycemia during the treatment session. During very long procedures, the dental team should consider having patients check their glucose with their glucometer part-way into the procedure.

One other factor that exerts a major influence on any diabetic patient’s risk of hypoglycemia is the medication that he or she is taking. More than a half dozen types of insulin are now routinely prescribed, along with several times that number of oral agents, and while some of these pose very little added risk for hypoglycemia, others are associated with high risk.^3,9

The various types of insulin in common use today have different times of peak activity. Blood glucose levels will reach their lowest point shortly after the peak activity of the insulin taken. Given the various injection regimens that patients follow, it may not be possible to schedule dental treatment to avoid a time when the patient’s blood glucose levels are decreasing. However, an awareness of what regimen any individual patient is on, coupled with a knowledge of the pharmacodynamics of the insulin being used prior to the treatment can help to prepare the dentist for the possibility of a hypoglycemic event.

Among the oral agents in common use for type 2 diabetes, several pose little risk for hypoglycemia. However, some stimulate increased pancreatic insulin secretion, and this does increase the hypoglycemia risk. It is important for any diabetic patient who is taking one of these medications (either sulfonylureas such as glyburide, glipizide, or glimepiride, or meglitinides such as repaglinide or nateglinide) to eat before dental treatment. The treating clinician should confirm that this has occurred.

Dentists should base their clinical care on science. However, it is important to remember that science is based on means and standard deviations, whereas clinical care must focus on the individual person sitting in the dental chair—and that patient may or may not be average. As the standard bell curve illustrates, only two-thirds of the people in any dental practice fall within the average range, plus or minus one standard deviation. In effect, the science may not apply to a third of the patients; thus, some people with well-controlled diabetes will still have periodontal disease, and some with very poorly controlled diabetes will have a healthy periodontium. On average, however, attention to the principles discussed in this article can help to improve both the oral status and overall health of patients with the pernicious and increasingly common disease that is diabetes.

Brian L. Mealey, DDS, MS
Professor and Graduate Program Director
Department of Periodontics
University of Texas Health Science Center at San Antonio Dental School
San Antonio, Texas

Robert J. Genco, DDS, PhD
Vice Provost of Office of Science
Technology Transfer, and Economic Outreach, and Distinguished Professor of Oral Biology
Periodontics, Microbiology
University at Buffalo
Buffalo, New York

Rachel A. Schallhorn, DDS, MS
Private Practice
Aurora, Colorado