Insulin is a hypoglycemic hormone secreted by pancreatic beta cells, and insulin is the only hypoglycemic hormone in the body. There are two cases of excessive insulin secretion as follows: i. Excessive insulin secretion with normal or elevated blood glucose suggests that the patient has insulin resistance. When a patient has insulin resistance due to obesity and other reasons, the body must promote more insulin secretion in order to maintain normal blood glucose, and when the increased insulin still cannot control blood glucose in the normal range, elevated blood glucose or even diabetes will occur. Second, if excessive insulin secretion is accompanied by hypoglycemia, it indicates that the patient may have inappropriate excessive insulin secretion. Under normal circumstances, the body will reduce insulin secretion when hypoglycemia occurs and stop insulin secretion when blood glucose concentration is lower than 1.67 mmol/L. If insulin secretion is still too much when hypoglycemia occurs, it is necessary to further exclude inappropriate excessive insulin secretion, such as insulinoma.