In general, symptoms of diabetes vary from patient to patient, but xerostomia or dry mouth is a common symptom in most patients with diabetes.
Diabetes is a metabolic disorder caused by a chronic high blood sugar level that is due to a defect in the production or the action of insulin, which prevents the correct metabolism of carbohydrates, fats, and proteins.
Insulin is a hormone produced by the pancreas needed for glucose to enter the cells, so they can obtain energy.
If the body cannot make insulin (type 1 diabetes), or if it doesn’t make enough or it is not used properly (type 2 diabetes), glucose remains in the blood.
Over time, the high levels of glucose in the blood can cause renal, neurological, cardiac, or vascular damage and vision problems (even blindness), amongst others. The mouth is not spared from the complications of diabetes, and diabetics usually suffer from gingivitis, periodontitis, tooth loss, mouth sores, and dry mouth.
Diabetes may not cause evident symptoms, and indeed there are people suffering from diabetes who are unaware of their condition. It is estimated that a third of diabetics remain undiagnosed. Some of the symptoms of diabetes can be confused with symptoms of other diseases, and go unnoticed if are not considered together. These symptoms include weight loss, fatigue, blurred vision, excessive thirst (polydipsia), excessive or abnormally large production of urine (polyuria), dehydration, and dry mouth.
As we said at the beginning, dry mouth and a lack of saliva are two of the symptoms frequently appearing in people with diabetes, and in fact should be taken as a sign or an alert for a possible diagnosis of diabetes.
Why does diabetes cause dry mouth?
Diabetes is a systemic disease, that is, it affects the whole body. Mouth dryness due to diabetes can have multiple causes depending on the type of diabetes and its complications.
Dry mouth in type 1 diabetes is usually due to high levels of glucose in the blood causing dehydration, nerve damage (neuropathy), and anti-diabetic drugs.
In type 2 diabetes, dry mouth is usually caused by drugs used to lower blood sugar levels and dysfunction of the autonomic nerves.
Diabetes causes dehydration, directly related to elevated blood glucose levels. Kidneys, one of the organs most affected by the disease, cannot reabsorb excess blood glucose, so they start to excrete it into urine, which draws water into the urine, causing polyuria. Excessive urination dehydrates the body, increasing the sensation of dry mouth and causing excessive thirst.
Variations in blood glucose levels immediately affect the production of saliva, and a low level of saliva may be indicative of disease progression.
Neuropathy (nerve damage)
Another factor that can cause lessened production of saliva is nerve damage.
Diabetic neuropathy is a complication of diabetes affecting usually peripheral nerves (peripheral neuropathy). The peripheral nervous system controls muscles, skin, internal organs, and glands, and it is subdivided into the somatic nervous system and the autonomic nervous system. It functions unconsciously and regulates bodily functions such as breathing, involuntary blinking, digestion, sweating, and salivation.
Peripheral nervous system disfunction caused by diabetes (autonomous peripheral neuropathy) can cause damage to the salivary glands and decrease of salivary flow.
Some drugs used to treat diabetes (such as metformin or thiazolidinediones, amongst others) or to control its complications frequently cause dry mouth as a side effect.
How can you prevent xerostomia or dry mouth if you are diabetic?
Keep your diabetes under control
You can prevent a lot of complications if you keep your diabetes under control. Studies linking diabetes and xerostomia have found a relation between uncontrolled glucose levels and lower saliva production.
If you have symptoms of dry mouth and are on antidiabetic drugs, ask your doctor if there are other drugs for diabetes that don’t cause this side effect.
Practice good oral hygiene
When you have diabetes it is very important to keep your mouth healthy, as you may be prone to gingivitis or periodontitis. These problems may cause gum destruction, which in a diabetic patient tends to heal slowly (just like other wounds).
Furthermore, the lack of saliva may cause mucosal irritation, tongue fissures, and painful mouth sores. Root decay or root caries are common, as well as fungal infections, like thrush.