From Volume 41, Issue 2, March 2014 | Pages 144-154
The prevalence of diabetes is increasing significantly and, therefore, dental practitioners are having to manage diabetic patients on a more regular basis. Alongside the systemic effects on the various tissues and organs of the body, diabetes can adversely affect oral health and all clinicians should be aware of the issues that may arise.
Diabetes mellitus describes a metabolic disorder of multiple aetiologies, primarily affecting the utilization of carbohydrates. It is a chronic disease recognized by hyperglycaemia secondary to insufficient insulin production by the pancreas or inability of the body to utilize the insulin it produces effectively.1 Depending on the pathogenesis, diabetes mellitus may be classified as Type 1 or Type 2.
Type 1 diabetes mellitus is a deficiency of insulin secretion, usually due to auto-immune damage of pancreatic β-cells. It is considered to be a condition of the young as the peak onset is around puberty and usually starts to affect patients of less than 20 years of age. It accounts for 10% of all diabetic cases and higher rates of the condition are found in Caucasians, especially those of North European origin.2,3
Type 2 diabetes mellitus describes a condition of insulin resistance, where the utilization of endogenously produced insulin at target cells is altered. Auto-immune destruction of β-cells does not usually occur and, although patients retain the capacity for insulin production, it may be reduced in some instances.4 The condition most often presents in middle and older age, although it is now more frequently diagnosed in younger overweight individuals. Type 2 represents 90% of all cases of diabetes mellitus in the UK and is up to three times more common among those of Asian, African or Afro-Caribbean decent.3,5
It is estimated that the current global prevalence of diabetes is 346 million.6 There is currently a total of 2.6 million people diagnosed with diabetes in the UK with a further estimated half a million undiagnosed.7,8 The prevalence of diabetics is growing rapidly in the UK, with the condition estimated to affect over 4 million people by 2025. Most of these cases are expected to be of Type 2 diabetes, because of the ageing population and rapid escalation of overweight and obese individuals.9
The exact cause of diabetes mellitus is unknown, though the risk of development is dependent on a number of factors. These include genetics, lifestyle and environmental factors. Though the condition is not genetically predetermined, increased susceptibility can be inherited and triggered by environmental determinants. The risk of developing diabetes if both parents are affected is up to 30% for Type 1 and 75% for Type 2, whilst identical twin concordance is at 40% and 90%, respectively, implying that non-genetic factors must also be involved.10
Almost two out of three people in the UK are overweight or obese and Type 2 diabetes has a strong association with obesity.11 There is increasing evidence that obesity has significant pro-inflammatory effects, which cause chronic activation of the innate immune system and alterations of glucose tolerance.12
Low socio-economic status is strongly associated with higher levels of obesity, physical inactivity, unhealthy diet, smoking and poor blood pressure control, as well as lower education and worse access to services. These factors are intimately linked to the risk of diabetes and its complications, with the most deprived populations two and a half times more likely to have diabetes at any given age than the average.13 These factors should be considered when assessing and managing dental patients.
The classic features of diabetes mellitus are common to both Types 1and 2 and include polyuria (excessive urination), polydipsia (excessive thirst) and polyphagia (excessive hunger). Continued hyperglycaemia leads to unexplained weight loss and fatigue, which may progress to ketoacidosis if early symptoms are not recognized and managed, especially in Type 1 diabetes. Some patients may experience episodes of blurred vision.14 The onset of Type 1 is usually abrupt in comparison with Type 2, in which patients may be asymptomatic for a long time before the appearance of complications.
Diagnosis is usually confirmed by a single laboratory glucose measurement showing hyperglycaemia and may be supported by raised HbA1C (glycosylated haemoglobin). A plasma glucose test is the most effective method of detecting hyperglycaemia. The World Health Organization (WHO) criteria for diabetes diagnosis recommends a fasting plasma glucose level of >7.0 mmol/L or random plasma glucose level of >11.1 mmol/L as diagnostic in symptomatic individuals.2 Though HbA1C is used to monitor long-term glycaemic control in a diagnosed patient, it is not recommended for diagnosis.
The value of using HbA1C to monitor patients lies with its reflection of long-term glycaemic control. Numerous proteins in the body are capable of being glycosylated and, in the case of haemoglobin, its binding to glucose in erythrocytes is a highly stable process, with haemoglobin remaining glycosylated for the lifespan of erythrocytes, approximately 123 days.12 Therefore, detecting the level of glycosylated haemoglobin in the blood accurately reflects mean blood glucose concentration over the preceding 1–3 months. This is the HbA1C value and the recommended target is <7.0% (normal is 6.0%).2
Clinicians can use this data to obtain a more inclusive representation of the long-term glycaemic control of their patients and it is encouraged that dentists enquire about patients' HbA1C readings on a regular basis.
Pre-diabetes is a condition in which blood glucose levels are elevated but have not yet reached diabetic diagnostic thresholds. It is a high risk state for diabetes and approximately 5–10% of people with pre-diabetes will progress to Type 2 diabetes.15 The condition is associated with the underlying β-cells dysfunction and insulin resistance, which begin before blood glucose changes are detectable. Most sufferers will not show any signs or symptoms and therefore diagnosis is difficult. However, some may develop similar clinical features to those of diabetes as blood glucose approaches diagnostic levels.15 Of particular concern are symptoms of excessive thirst and a dry mouth, despite normal fluid intake. It is important to investigate complaints of dry mouth and consider pre-diabetes as a cause in the absence of other aetiological factors.
Research has shown that long-term damage to the body may already be occurring during pre-diabetes. Patients suspected of being pre-diabetic must be referred for blood glucose testing for confirmation of diagnosis. Lifestyle modification is the cornerstone of diabetes prevention, with evidence of a 40–70% risk reduction.8,15
It is well recognized that the pathogenesis of diabetes mellitus induces long-term irreversible damage of various tissues and organs. Chronic hyperglycaemia plays a major role in the production of several systemic complications and this considerably reduces life expectancy. These complications can be categorized as macrovascular and microvascular.
These are responsible for the majority of the morbidity and mortality associated with the disease. Hyperglycaemia predisposes to atherosclerosis and vascular obstruction, which is accountable for the increased likelihood of coronary artery disease, cerebrovascular disease and peripheral vascular disease.14 These patients are twice as likely to experience strokes and three to five times more likely to experience myocardial infarctions.2
These tend to manifest 10–20 years after diagnosis in young patients and result from the chronic hypertension associated with macrovascular obstruction. They typically include:14
The suspected cellular events that lead to this micro-and macroscopic damage relate to the enzymatic glycosylation of glucose and the production of chronic elevated levels of intra-cellular advanced glycosylated endproducts (AGEs). This process involves the glycosylation of glucose into proteins within tissues including albumin, collagen, lipo-proteins and proteins within myelin. Chronic hyperglycaemia leads to elevated levels of glucose within cells that do not require insulin for its uptake (are unable to reduce glucose intake) – nervous tissue, lens of the eye, kidney, vascular. Subsequently, elevated levels of AGEs are produced and, once incorporated into the proteins within these insulin-independent cells, lead to deterioration in their function. These changes are considered largely irreversible.16
In addition, hyperglycaemia activates the transcription factor, nuclear factor-κB. This alters the phenotype of macrophages and results in increased production of pro-inflammatory cytokines, such as interleukin-1 and tumour necrosis factor-α.12 These cytokines also contribute to the formation of atheromatous lesions.
It is currently estimated that 10% of the total NHS budget is spent on diabetes, approximately £9 billion per annum.17 Most of this is directed at treating the complications of the condition and so it is understandable that effective management is aimed towards prevention. The main goal of diabetes management is to maintain near normal blood glucose levels and maintain a normotensive blood pressure. This can be achieved using a combination of medications and lifestyle changes.2,17 (Table 1).
| Type of Diabetes | Management |
|---|---|
| Type 1 (Insulin dependent) | Insulin therapy: |
| Type 2 (Non-insulin dependent) | Address associated risk factors sequentially-severity dependent: |
Newer agents on the market include natural hormone analogues such as amylin (Symlin®, Amylin Pharmaceuticals Inc) and exenatide (Byetta®, Amylin Pharmaceuticals Inc), which modulate gastric emptying and insulin secretion, respectively. Whilst evidence exists to support their use, their high cost means that they are not currently widespread.12
Self-monitoring is the only direct method by which diabetes sufferers can evaluate their level of control of blood glucose.2 It also helps prevent the consequences of extreme hyperglycaemia or hypoglycaemia. Self-monitoring offers several advantages to the patient,2 such as providing a heightened awareness of the condition, giving personal gratification when readings are low, and cultivates independence from health services and enhances self-regulation. Self-monitoring should be encouraged. The pin-prick test is the most common method for monitoring blood glucose and involves the use of a digital glucose meter. Some patients favour urine glucose monitoring. The need and extent of testing is individual to each patient and will depend on the treatment regime and degree of glycaemia control. However, blood glucose levels can be affected by physical activity, diet and medications. Therefore, to interpret results, it is important to consider all of these factors.
It is important for clinicians to be aware of their patients' management regimes and diabetic control to aid in provision of care and in preparation for possible diabetic emergencies. This necessitates accurate and up-to-date history-taking.
It is widely acknowledged that diabetes mellitus can present itself in a variety of manifestations within the oral cavity. Dentists are almost guaranteed to encounter patients with diabetes and, therefore, it is important to be aware of the oral signs and symptoms of poorly controlled or undiagnosed diabetes (Table 2).
| Manifestation | Aetiological Mechanism | Effects/Risks |
|---|---|---|
| Xerostomia | Unclear: |
Caries |
| Caries |
|
Caries in low risk areas, eg cervical and root caries |
| Candidosis | Pseudomembranous Candidosis |
|
| Periodontal Disease |
|
Impaired glycaemic control further increasing risk of periodontal disease |
A dry mouth is a common complaint of diabetics, the exact cause of which is unknown. Though often associated with salivary gland dysfunction, it may be related to polyuria in hyperglycaemia. An increase in salivary glucose levels has also been detected in diabetics, resulting in more viscous saliva and the symptom of a dry mouth.18 Any change in the quality or quantity of salivary protection will affect oral health, especially if chronic in nature, and so it remains important for dentists to follow-up diabetic patients on a regular basis.
There is no clear evidence demonstrating the association between diabetes and caries per se though dentists should note that diabetic patients may be subject to an increased risk of dental caries; reduced salivary output in combination with higher salivary glucose content provides an exceptional culture medium for bacteria thus leading to a high caries risk. However, clinicians must not overlook the importance of oral hygiene measures and dietary management as research suggests that, in the presence of these, diabetic patients are at no greater risk than the general population.19 Dentists should encourage patients to comply with dietary advice and stress the importance of good diabetes control in order to reduce their risk, and should monitor closely those patients with evidence of high caries activity, such as cervical and root caries.
Diabetics may have an increased susceptibility to oral infections. This is related to the effects of chronic hyperglycaemia on the immuno-inflammatory system, which include impaired neutrophil chemotaxis and phagocytosis resulting in relative immunosuppression.20
Opportunistic infections, such as oral candidosis, are more common in diabetic patients. Salivary hypofunction contributes to this in poorly controlled diabetics. Additionally, oral epithelial cells are more receptive for Candida in diabetes.21,22 Nevertheless, it is important to consider other underlying causes when candidosis is detected, especially in a well-controlled diabetic, and clinicians should refer patients for appropriate investigations when in doubt.
It is well reported that there exists an increased incidence of gingival inflammation and alveolar bone loss in poorly controlled diabetics.12,23 The mechanisms by which diabetes influences the periodontium are similar to the pathophysiology of the classic microvascular and macrovascular diabetic complications. There are few differences in the subgingival microflora of diabetic and non-diabetic patients, with periodontitis12 suggesting that alterations in the host immuno-inflammatory response to pathogens may play a predominant role. Though compromised neutrophil function has been found in diabetics, these patients show a hyper-responsive macrophage phenotype resulting in significantly higher levels of local pro-inflammatory mediators and reduced collagen metabolism, in comparison to systemically healthy individuals with periodontitis.12,24 Additionally, the increased glucose content in gingival crevicular fluid may facilitate bacterial persistence in the periodontal pocket.12 The relationship between the two conditions may be reciprocal. There is some evidence suggesting that periodontal health also affects glycaemic control.18,25 Indeed, treating periodontal disease in diabetic patients has also been shown to improve glycaemic control.12,18,25
Of course, the presence of periodontal disease represents a unique opportunity for oral pathogens to gain access to the systemic circulation. This periodontitis-induced bacteraemia can induce a chronic, elevated systemic inflammatory state with increased serum C-reactive protein, interleukin-6 and cytokine levels.26 Therefore treating periodontal infections may be important in the management of diabetes. This is an interesting development that requires significant further investigation, however, the concept of dental treatment influencing medical management of patients is clearly of major significance.
Wound healing is unlikely to be of concern in the oral cavity unless patients have undergone invasive oral surgery. Contrary to belief, this is usually unaffected, unless a patient is suffering from long-standing hyperglycaemia.12 However, many diabetic patients do not have adequate glycaemic control and so it is highly likely that dentists will encounter patients with reduced or delayed wound healing. The increased levels of matrix metalloproteinases observed in diabetics may result in altered collagen homeostasis and wound healing and, while impaired phagocyte and macrophage function may also contribute, the true pathogenesis of delayed healing in diabetes remains poorly understood.26
It remains important to monitor patients who demonstrate slow healing following surgery closely. Those suspected of having poorly controlled or undiagnosed diabetes should be referred to their General Medical Practitioner (GMP) for further investigation.
It is imperative when treating diabetic patients to obtain an up-to-date, accurate medical history. Clinicians should anticipate possible diabetes-related complications which may impact on dental care. Dentists should liaise with a patient's GMP in the event that further medical treatment is required prior to the provision of dental care. The practitioner checklist is an aid to ensure clinicians do not omit important information from the patient's diabetic history (Table 3).
Patients with well-controlled diabetes are suitable for dental treatment and minor oral surgery procedures in general practice. This can be carried out under local anaesthesia, inhalation sedation and intravenous sedation. Those with poor glycaemic control and/or severe complications may need to be referred into secondary care in a hospital setting.
Consideration should be given to the timing and length of appointments of diabetic patients, as dental appointments should not interfere with their control regime. By doing so, the dentist can provide stress-free appointments and reduce the risk of diabetic emergencies. Early morning and early afternoon appointments are preferred because they are less likely to disturb food and drug routines, thus reducing the risk of hypoglycaemia.
Many dentists debate the use of prophylactic antibiotics for diabetic patients. There is currently no evidence to support this practice for well-controlled diabetics, as these are at no greater risk of post-operative infection than healthy individuals.27 Antibiotic prophylaxis should only be considered in situations where it would be used for a systemically healthy patient and for patients with unstable diabetes undergoing invasive dental procedures.27 Poorly-controlled patients will require referral to their GMP for correction of their glycaemic control before further elective dental work is planned. It should also be remembered that patients who have an existing infection may experience difficulty in controlling their blood glucose levels and thus may enter a cycle of deterioration if not managed appropriately or promptly.
Prevention and early intervention are key characteristics of both diabetic and dental care. It is crucial that patients who are at risk from diabetes are identified and managed appropriately. Regular oral health examinations are imperative and patients should be educated that diabetes is a risk factor for oral health and that their own oral health may impact on their diabetic control and general health.
Treating the diabetic patient means that the dental team can be faced with the task of managing acute complications such as hypoglycaemia and ketoacidosis (hyperglycaemia). It is the responsibility of the dentist to ensure that his/her team is able to deal with medical emergencies that may arise and provide treatment, if required.
Hypoglycaemia is the most likely medical emergency to occur in the dental setting. Note that many patients still believe that they should starve before visiting the dentist. For this reason, it is imperative that all members of the dental team check that a diabetic patient has eaten before treatment commences. Starving before treatment should be discouraged and patients should be advised to maintain their usual dietary and treatment regime. In most cases of hypoglycaemia, the patient will remain conscious and responsive. This can be reversed with a simple oral glucose drink or proprietary product, eg Glucogel® (BBI Healthcare). In more severe cases, where the patient has impaired consciousness or is unable to swallow oral glucose, an intramuscular injection of glucagon will be required. Alternatively, a 10% or 20% glucose IV solution may be used if venous access is available, ie during IV sedation. If in doubt, insulin administration should be avoided at all costs as this may lead to brain damage or death in a hypoglycaemic patient28 (Table 4).
| Emergency | Precipitating Cause | Symptoms | Management |
|---|---|---|---|
| Hypoglycaemia (glucose <3.0 mmol/L) | Food omitted following insulin intake |
|
Co-operative and conscious: |
| Hyperglycaemia/Ketoacidosis | Insulin deficiency |
|
Ambulance summoned immediately for urgent hospital admission |
It is important that the patient's GMP is informed of any event and administered treatment.
Diabetes mellitus is a generalized disease with multiple aetiologies. It can affect oral health in several ways and the relationship is bidirectional in that good oral health improves glycaemic control. Effective communication between the dentist and GMP allows co-ordination of multidisciplinary care to slow progression of disease and reduce the risk of developing complications. Regular screening will aid in identifying those who require further attention and investigation and so it is important that the dental team is aware of the signs and symptoms of poorly-controlled or undiagnosed diabetes. Furthermore, dentists should educate their patients that diabetes is a risk factor for oral health and that their oral health may impact on their diabetic control and general health.
