Type 1 diabetes insulin three hours after meals blood glucose rose to 20mmol / L, may be due to improper application of drugs, or due to dietary habits, easy to occur diabetic ketoacidosis and other emergencies, it is recommended to promptly seek medical attention to adjust the type of insulin, dosage or injection time, and pay attention to dietary control, if the occurrence of ketoacidosis in a timely manner first aid. 1. Improper application of drugs: If the blood sugar is too high three hours after meals, the type of insulin or the injection time may be unsuitable (e.g., short-acting insulin is injected too early) or the injection dose is not enough. At this time, you should consult a doctor to adjust the medication. 2. Dietary habits: Excessive consumption of food with too much sugar content can also lead to an increase in blood glucose three hours after meals. It is recommended that patients should pay attention to dietary control and avoid foods with too much sugar content while using insulin and other drugs. 3. Others: If the patient is stressed for a short period of time, adrenaline, glucocorticoids and other glucagon hormones are secreted in large quantities, which may also lead to a significant increase in blood glucose; blood glucose 20mmol/L should be alert to the occurrence of diabetic ketoacidosis and other emergencies, and emergency treatment should be given in a timely manner. It is recommended that patients seek timely medical attention.