Although dry mouth is one of the typical symptoms of diabetes, the characteristics and severity of dry mouth are not used to determine whether diabetes is present.
In addition to dry mouth, diabetes can also present with acute metabolic disturbances such as excessive drinking, polyuria, polyphagia, weight loss, pruritus, blurred vision, etc. Diabetes can be diagnosed when a patient presents with these symptoms and has a random blood glucose ≥ 11.1 mmol/L, or a fasting blood glucose ≥ 7.0 mmol/L and a 2h glucose load test ≥ 11.1 mmol/L. The higher the blood glucose value in diabetic patients, the more severe the dry mouth symptoms often are.
Therefore, although the characteristics of dry mouth do not clearly indicate a diagnosis of diabetes, they may reflect to some extent how well a diabetic patient has controlled their blood glucose.