Typical symptoms of diabetes mellitus include “three more and one less”, i.e., excessive drinking, excessive eating, excessive urination and weight loss. The symptoms of diabetes mellitus are individualized and may vary from patient to patient. In addition to the above symptoms, some patients may have itchy skin, especially on the vulva. The rapid increase in blood glucose can cause changes in the osmotic pressure of the aqueous humor and the lens, resulting in refractive changes and blurred vision. Most type 2 diabetes mellitus has an insidious onset and relatively mild symptoms, with more than half of the patients having no symptoms at all; many patients are suffering from chronic complications, concomitant illnesses, or are only detected during health checkups. If the above symptoms occur and diabetes is suspected, it is recommended to go to the endocrinology department of a regular hospital in time to avoid delays.