To know if you have diabetes, you first need to understand what is diabetes? The current medical definition of diabetes is as follows: diabetes is a group of clinical syndromes of disorders of sugar, lipid and protein metabolism caused by the lack of insulin and/or the failure of insulin to function properly in the body. The common feature is a chronic hyperglycemic state. In short, diabetes is a condition in which the body has “elevated blood sugar”. Severe hyperglycemia can lead to acute complications of diabetes, such as diabetic ketoacidosis and hyperglycemic hyperosmolar syndrome. If not treated in time, it can be life-threatening at any time. Due to the development of China’s social economy and the gradual improvement of medical conditions in urban and rural areas, the above critical conditions brought about by diabetes have been greatly reduced, and replaced by disabilities (including stroke, gangrene, heart disease, kidney failure, loss of vision), reduced quality of life, and the burden of transdose caused by chronic complications of diabetes due to long-term failure to control the disease well. Strictly speaking, the root cause of elevated blood glucose is the body’s inability to use sugar properly rather than due to excessive intake. In normal people, there is almost no sugar in urine. When the elevated blood glucose exceeds the limit of renal reabsorption, excessive sugar will be excreted in urine, and the urine will be positive for sugar. The urine excretes sugar while taking away a lot of water, so there is “polyuria”. The excessive urination will cause the body to be short of water, making people feel thirsty, and thus “thirsty and drink a lot”. As we all know, the staple food (rice, noodles, etc.) we take in three meals a day is mainly converted into glucose in the blood after digestion and absorption, which is the main source of energy for daily physical and mental work, and the blood sugar mentioned above refers to the glucose in the blood. Since glucose cannot be used by the body for energy and is retained in the blood circulation, blood glucose rises. At the same time, the brain’s food intake center is stimulated, feeling hungry all day long, appetite increased and “easy to eat”. However, this kind of overeating is harmful but not beneficial to the human body, because the state that the body cannot use glucose is not improved, but the overeating further worsens the already elevated blood sugar, playing the role of “adding fuel to the fire”. In order to compensate for the lack of energy, the body will seek other alternative ways, that is, to use the body’s spare “food” to compensate, in order to exercise the role of glucose energy supply. This “spare food” includes “fat” stored in adipose tissue, and “protein” stored in muscle tissue. As fat and protein are continuously mobilized and consumed, the body becomes thin, the person becomes weak, loses weight, and is prone to various infectious diseases due to decreased resistance, and surgical wounds and even minor trauma are difficult to heal. As a result, the typical symptoms of diabetes “three more and one less” all come out: “drinking more, eating more, urinating more and losing weight”. Therefore, the “three more and one less” symptoms are important clues to detect diabetes. However, unfortunately, most diabetic patients do not have typical symptoms or any symptoms at all in the early stages of the disease. In order not to delay the diagnosis and treatment, the most advisable way is to have blood tests for fasting and 2-hour postprandial glucose at the hospital on a regular basis for early diagnosis and treatment.