According to a study, 76.4% of diabetic patients present with xerostomia, a symptom that can favour the development of multiple oral diseases and disorders. 

Xerostomia is a subjective perception that the patient describes as the feeling of having a dry mouth. It should be noted that it is not always related to a salivary gland dysfunction, and that it can be caused by dehydration, oral sensory disorders, certain psychological conditions, central cognitive impairment or certain medications, among other factors. 

It is an oral condition that is increasingly encountered in daily practice due to its multifactorial aetiology: polypharmacy, cancer treatment, stress, old age, etc. 

One cause is diabetes mellitus, a metabolic disease characterised by chronic hyperglycaemia. There are two types of diabetes mellitus, type I and type II. In type I, insulin secretion is absent due to the destruction of pancreatic β-cells. Type II diabetes is due to the resistance of peripheral tissues to insulin and/or to a relative decrease in insulin secretion. 

The prevalence of diabetes has mushroomed in recent years and has become a public health issue, especially in developed countries. One study found the prevalence of xerostomia in diabetic patients to be 76.4%. In the long term, hyperglycaemia results in systemic complications such as cardiovascular disease, neuropathy and nephropathy. 

In addition, oral manifestations of uncontrolled diabetes are important, such as problems related to saliva secretion, periodontal disease, slow wound healing and burning mouth syndrome. 

The control of blood glucose is a key factor in the onset and development of many oral signs and symptoms. A decrease in saliva and dry mouth favour the appearance of: 

• Tooth decay 

• Oral candidiasis 

• Difficulty swallowing and speaking 

• Periodontal disease 

• Oral biofilm build-up. This complication can affect the quality of life of patients, so it must be properly diagnosed.