Blood sugar mainly refers to the glucose in the blood, which comes from two sources: 1, from food. The main component of the rice and noodle food we eat is starch, which is digested and broken down into glucose in the digestive tract, and then absorbed into the blood by the small intestine to become blood sugar, which is the main source of blood sugar. 2.Transformation in the body. The conversion of other substances in the body (such as glycogen, fat, protein, etc.) into glucose is another way of blood sugar. Under normal circumstances, there are two ways for blood sugar to go: 1. The blood carries glucose around the cells, and the sugar then leaves the blood vessels, enters the cells under the action of insulin, and is consumed by the cells. This is the most important route for blood sugar. 2. The other route for glucose is to be converted into other substances (such as glycogen, fat, protein, etc.). In diabetes, glucose is excreted in the urine, which is an abnormal route for blood sugar.