If a patient experiences significant symptoms of dry mouth, excessive thirst, increased urination with more foamy urine, increased appetite, but an unexplained weight loss, known as the "three polys and one low" symptoms, it is necessary to monitor fasting blood glucose. If the fasting blood glucose exceeds 7.0 mmol/L or the blood glucose two hours after a meal exceeds 11.1 mmol/L, or if there are no clear "three polys and one low" symptoms but random blood glucose levels exceed 11.1 mmol/L on two occasions, a diagnosis of diabetes can be confirmed.

At the same time, it is essential to rule out secondary effects on blood sugar levels caused by infections, trauma, or the use of steroid medications. It is also recommended that the patient undergo tests for glycated hemoglobin, as well as insulin and C-peptide release tests, to further clarify the diagnosis.