What is blood sugar Blood sugar, usually refers to the free glucose in the blood. In a healthy person, blood glucose can be maintained in a relatively constant range under normal conditions, both on a fasting and a full stomach. In a normal person, fasting blood glucose is less than 6.1mmol/l , and two hours after meal, blood glucose is less than 7.8mmol/l. In the regulation of blood glucose, the key role is played by insulin secreted by the pancreas. After eating, food is digested and decomposed into glucose in the stomach and intestines, which is absorbed into the blood as blood sugar, and it is the main source of energy for the body. In the liver, insulin promotes the synthesis of glucose into glycogen, the storage form of sugar; if insulin is compared to a banknote, glycogen is the depository, which can be converted into glucose again when needed. In the liver, a small portion of glucose is also converted into fat for storage; in adipose tissue, insulin promotes the conversion of glucose into fat for storage; and in somatic cells, insulin promotes the utilization of glucose. The end result is that blood glucose levels fall and are controlled by insulin. When the pancreas cannot secrete enough insulin or the secreted insulin is impaired in its action and does not function properly for a variety of reasons, blood glucose rises and the excessive blood glucose is excreted in the urine as diabetes. Diabetes mellitus is a chronic disease characterized by high blood sugar. The diagnosis of diabetes is mainly based on blood glucose. According to the latest American Diabetes Association diagnostic criteria, the current diagnostic criteria for diabetes are 1. fasting plasma glucose concentration ≥ 7 mmol/L 2. 2-hour plasma glucose concentration ≥ 11.1 mmol/L during oral glucose tolerance test 3. random venous plasma glucose concentration ≥ 11.1 mmol/L 4. glycosylated hemoglobin ≥ 6.5% Note that these four items are or are related to each other. As long as one of them is not normal, it is considered abnormal. In terms of this diagnostic criteria, there are several points: 1. blood glucose refers to venous plasma glucose 2. to exclude stressful situations (in terms of clinical diagnosis, acute infection, trauma or other stressful situations can appear temporary increase in blood glucose, if there is no clear history of hyperglycemia, it is not possible to diagnose diabetes with the blood glucose value at this time, it is necessary to review and determine the state of glucose metabolism after the stress is eliminated). 3.If the patient has typical diabetic symptoms or acute complications of diabetes, one test can be used as the basis for diagnosis. 4.For patients without symptoms, two tests are needed to exclude test errors. The same items can be tested at different times, or different items can be tested twice to meet the diagnostic criteria as the basis for diagnosis Several concepts Fasting blood glucose refers to: no calorie intake (energy) for more than 8 hours Generally, patients do not eat after 8:00 p.m., and venous blood is drawn in the morning on an empty stomach Random blood glucose refers to: blood glucose concentration at any time, regardless of whether or not to eat Oral glucose tolerance test is commonly used in clinical diagnosis of diabetes and assessment of pancreatic islet function Method: Briefly introduce the test procedure 1, the test is conducted in the morning on an empty stomach 2, the doctor will prescribe 75g of glucose powder, dissolve the powder in about 300ml of water, before eating sugar water, that is, 0 minutes, and since eating sugar water 30, 60, 120, 180 minutes respectively to draw venous blood to test glucose, or you can take the simple method to draw only 0 minutes and 120 minutes of Venous blood for glucose testing 3, only after the test can eat 4, avoid strenuous exercise during the test Glycosylated hemoglobin: is the product of the combination of hemoglobin and glucose, it responds to the average level of blood glucose in the body for 8-12 weeks, since 2012, glycosylated hemoglobin > 6.5% as the diagnostic criteria for diabetes.