Inability to control blood glucose by insulin generally refers to diabetic patients whose blood glucose remains high after using insulin, which may be caused by the development of insulin resistance or insufficient insulin dosage. Strict dietary control, supplemental oral medications, adjusting insulin dosage, changing insulin type, etc. are often used in clinical treatment. 1. Strict dietary control: some patients do not have strict dietary control despite the use of insulin. Consumption of too much greasy and sugary food will also affect blood glucose, and the total calorie intake per day should be controlled, including the intake of carbohydrates, fats, proteins, and so on. 2. Auxiliary oral drugs: insulin sensitizers can be added, such as metformin hydrochloride tablets, rosiglitazone tablets, etc., as well as glucosidase inhibitors, such as acarbose tablets, etc., and insulin secretion promoters can also be applied jointly, such as gliclazide tablets, glibenclamide tablets, etc. 3. Adjusting insulin dosage: some patients may not be able to control their blood glucose due to insufficient insulin dosage, they should consult the doctor in time and adjust the insulin dosage under the doctor’s guidance. 4. Changing the type of insulin: If the patient’s blood glucose still can’t come down after using too much insulin, it suggests that the patient may have insulin resistance, and should change to other types of insulin under the guidance of doctor. To summarize, there are many reasons why blood glucose does not come down after using insulin, it is recommended that patients go to the hospital as soon as possible to clarify the reasons, if the blood glucose is high for a long time and active treatment is not taken, acute and chronic complications of diabetes mellitus may occur, which may jeopardize the patient’s life.