Early symptoms of diabetes mellitus include excessive drinking, excessive urination, excessive eating and weight loss, or symptoms that are not obvious. Diabetes mellitus is caused by a combination of genetic and environmental factors, and its main clinical manifestation is a disorder of glucose metabolism. It is categorized into type 1 diabetes, type 2 diabetes, gestational diabetes, and special types of diabetes. Type 2 diabetes tends to most of the early symptoms are less obvious, not easy to be found. Typical symptoms are three more and one less, i.e., drinking more, eating more, urinating more, and weight loss. When there are unexplained dry mouth and thirst, as well as increased food intake but unexplained rapid weight loss, it is recommended to go to the hospital for examination. Some diabetic patients also have blurred vision, can’t see things clearly or have trouble concentrating, get sleepy easily and get tired easily in the early stage. If you suspect that you have diabetes, you should go to the endocrinology department of the hospital for examination, make a clear diagnosis, and get treated as soon as possible under the guidance of the doctor.