Diabetes is accompanied by polyuria - loss of lliqor due to insulin inadequate quantity, which causes secondary dry mouth-xerostomia, due to not enough water for salivation

Also i think with diabetes,atherosclerosis occur ,,, so blood supply to salivary gland decreased with time and atrophy occur >>> lead to decreased saliva outcome from the gland

Dear Arvind: Systemic diseases such as diabetes and local factors of the dental system cause xerostomia and tongue and burning of mucous membrane. Three reasons are mainly responsible : i) The biological reasons include permanent changes in the intermittent glucose tolerance in the mouth, neurological problems, diabetic Polineuropathy, heavily modified swallowing habits (> 2000 - 24 ) , morphological and physio- pathological stimuli to the tooth system and hyposalivation due to parafunctional problems. ii) The psychosomatic reasons include on one side increased pain perception, stress, tension, suffering, sorrow and on other side hyper functions of the jaw muscles. iii) The psychosocial reasons are perceived dry mouth, fear of halitosis, pain medications and drug side effects (anti- Hypertonica , psychotropic drugs).

Subsequent sensations are in phases (with free intervals and cumulations in connection with experience, go with taste and smell disorders associated and are usually without finding peculiarities. Patients are predominantly (not exclusively) denture wearers. They have collapsed or disturbed lateral tooth support zones. They deny faults control. Their experience and behavior in everyday life is worst, at work and at leisure. They determine the social contacts. Increasingly, the patient no longer believe in healing. The consequences are sometimes complete withdrawal and avoidance of contact with other people. The sensations paralyze any activity that lust for life, the food, to entertainment.

The therapy is not only symptomatic. You must be holistic. The temporal relationship between oral treatments, a new prosthesis and the development of xerostomia is almost always misinterpreted by the patient. You suspect usually allergic reactions. Be in steady contact with your patient during acute phases. This is helpful.

Patients with uncontrolled diabetes have xerostomia due to dehydration and probably due to salivary gland basement membrane changes. Neuropathy has also been implicated. The latter causes taste changes and burning sensation.

SGLT1 expression increases in the luminal membrane of salivary gland ductal cells and the salivary flow decreases in diabetic and hypertensive rats, which may be related to sympathetic activity. This study highlights the water transporter role of SGLT1 in salivary glands, which, by increasing ductal water reabsorption, may explain the hyposalivation of diabetic and hypertensive subjects.

http://www.ncbi.nlm.nih.gov/pubmed/24499577

http://www.ncbi.nlm.nih.gov/pubmed/19238474

Very interesting  Geriatr Nurs. 2015 Nov 26. pii: S0197-4572(15)00369-9. doi: 10.1016/j.gerinurse.2015.10.014. [Epub ahead of print]

Influence of oral moisturizing jelly as a saliva substitute for the relief of xerostomia in elderly patients with hypertension and diabetes mellitus.

Dalodom S1, Lam-Ubol A2, Jeanmaneechotechai S1, Takamfoo L3, Intachai W4, Duangchada K5, Hongsachum B6, Kanjanatiwat P7, Vacharotayangul P2, Trachootham D8.

Presence of high levels of glucose in blood increases plasma osmotic pressure, which results in tissue dehydration all over the body including mouth. Decreased secretion of saliva adds to the problem of xerostomia.