Introduction

Diabetes mellitus is a state of hyperglycemia which is due to either insulin deficiency (type 1 DM) or insulin resistance (type 2 DM). The World Health Organization (WHO) has recently declared it to be a pandemic. Its prevalence has increased dramatically over the past few decades and it is expected to triple in the next decade. 

Diabetes mellitus is considered a leading cause of death due to its microvascular and macrovascular complications. The intensity of diabetic complications is usually proportional to the degree and duration of hyperglycemia.

Oral Manifestation

Any systemic disease has its manifestations in the mouth. Oral manifestations of diabetes mellitus may be due to impaired neutrophil function, increased collagenase activity, and a reduction in collagen synthesis, microangiopathy, and neuropathy.

• Dry mouth / xerostomia

• Dental Caries 

• Periodontitis - it is the 6th complication of diabetes mellitus 

• Oral candidiasis 

• Burning mouth

• Geographic tongue

• Increased tendency to infections

• Defective wound healing etc.

Dry mouth

Due to salivary gland dysfunction, there may be decreased salivary flow and change in composition causing xerostomia. It leads to difficulty in eating, speaking, increased susceptibility to dental caries, decrease the quality of a patient's life. Etiology may be due to microvascular changes in salivary gland basement membrane.

Dental caries 

Reduced buffering capacity of saliva, xerostomia, increase in glucose levels in saliva can lead to increased incidence of dental caries. Chronic hyperglycemia may cause irreversible pulpitis leading to pulpal necrosis.

Periodontitis 

It is the 6th complication of diabetes mellitus. Alterations in host defense response (such as neutrophil dysfunction), subgingival microflora, structure and metabolism of collagen, vascularity, and gingival crevicular fluid can be possible mechanisms of periodontitis.

Elimination of pathogens by treatment leads to decrease in inflammation, reducing insulin resistance. This decreases glucose levels. In adults, periodontal disease is the main reason for tooth mobility and consequently, loss of it. Therefore, treatment of periodontitis, in addition to lowering blood glucose levels, can prevent tooth loss.

Oral infections 

Decreased salivary flow, absence of antimicrobial effects in saliva, impaired defense mechanism, poor metabolic control can lead to increased susceptibility to fungal and bacterial infections.

Oral candidiasis is an opportunistic fungal infection. Higher candida colonization rate were reported in patients with type 1 diabetes. Candida-related lesions include denture stomatitis, angular cheilitis, and median rhomboid glossitis. 

Burning mouth 

It is due to poor glycemic control, metabolic alterations in oral mucosa, angiopathy, candida infection, and neuropathy

Mucosal changes

Coated and fissured tongue, geographic tongue, recurrent aphthous stomatitis, and some premalignant lesions including lichen planus can be associated with diabetes. These may be due to insufficient control of diabetes, immunological alteration, microcirculatory changes with decline of blood supply, xerostomia and alteration in salivary flow and composition, and smoking. Oral lichen planus occurs more frequently in type 1 DM than type 2 DM.

Poor oral wound healing 

Diminished blood flow and hypoxia, a reduction in innate immunity, decreased growth factor production, and psychological stress may attribute to poor wound healing.