With the improvement of people’s standard of living and medical care, the number of diabetic patients using insulin therapy is gradually increasing, but most patients do not really grasp how to adjust insulin according to their actual situation, which makes some unnecessary troubles appear in the process of insulin application. Here we briefly introduce some general knowledge of insulin therapy. Insulin preparations can be divided into three categories: rapid (short) effect, medium effect and long (slow) effect. Rapid-acting insulin mainly controls high blood sugar after 1 meal; medium-acting insulin mainly controls high blood sugar after 2 meals, with the 2nd meal being the main one; long-acting insulin has no obvious peak of action and mainly provides basal level insulin. At present, the application of injectable insulin is mainly seen in the following cases: 1, when the effect of oral hypoglycemic drugs is not good, the combination of oral hypoglycemic drugs and medium- and long-acting insulin can be used, that is, oral drugs during the day, plus one injection of medium-acting insulin before bedtime. 2. When blood sugar is still unsatisfactory, oral medication can be stopped and complete insulin treatment can be given by giving a mixture of rapid-acting and long-acting insulin, which is injected twice a day before breakfast and dinner. This method may have midday or (and) midnight hypoglycemia, but eating some snacks in the morning can prevent midday hypoglycemia, and injecting medium-acting insulin before bedtime instead of the mixed insulin before dinner can prevent midnight hypoglycemia. 3.Injecting rapid-acting insulin before meals three times a day, plus injecting medium-long-acting insulin before bedtime, and the sub-method can arrange meal time flexibly. 4.Flexible application, short-acting insulin plus long-acting insulin is injected before meals to imitate physiological insulin basal secretion. This method can adjust the use of insulin according to the schedule of meals and exercise, or the content of carbohydrates in the diet, and 1 to 2 U of insulin is given for every 10 to 15 g of sugar in the diet. 5. Insulin dosage is larger in insulin resistant patients, and thiazolidinediones, metformin or a-glucosidase inhibitors can be added. After insulin therapy is selected according to the condition, patients are required to closely monitor blood glucose and adjust insulin dosage in a timely manner. Patients who inject insulin multiple times a day or use insulin pump therapy should have their blood glucose tested ≥3 to 4 times a day, and the number of monitoring should be increased to 5 to 8 times when blood glucose does not reach the standard, dose adjustment or frequent hypoglycemia, including pre-meal, post-meal and bedtime blood glucose of each meal, and if necessary, monitor the nighttime 2 to 3 o’clock blood glucose. Blood glucose monitoring should be measured at the peak time of insulin action, and those who use short-acting insulin can choose to measure it before or 2 hours after meals, while those who use medium-acting insulin should increase monitoring at bedtime and 3:00 am. In order to reduce the number of monitoring times per day, you can choose different testing times every day, such as measuring blood glucose before meals on one day and after meals on another day; or measuring blood glucose after breakfast and dinner on one day, and measuring blood glucose before and after lunch and before bedtime and early morning on another day. This can not only understand the blood sugar changes at different times, but also reduce the number of tests per day. If there are symptoms of hypoglycemia or other discomfort, it should be monitored at any time. Based on the results of blood glucose testing, we need to set an appropriate amount and make timely adjustments. There are several ways to calculate the total daily dose when starting insulin therapy: ① Calculation according to body weight: 0.5~1U/(kg.d) for type 1 diabetes; 0.2~0.6U/(kg.d) for newly diagnosed type 1 diabetes; 1.0~1.5U/(kg.d) for adolescent type 1 diabetes, which requires more because of rapid growth and development in adolescence; 0.1~0.2U/(kg.d) for type 2 diabetes /(kg.d). ②According to the physiological requirement: normal people secrete 30～40U insulin per day, and start insulin can start from 24～40U/d. ③Estimated by fasting blood glucose (FPG): 0.25U/(kg.d) is given when fasting blood glucose is 8~10mmol/L. When fasting blood glucose >10mmol/L, insulin increases by 4U/d for every 1mmol/L increase. After calculating the total amount of insulin required daily, we have to divide it reasonably before three meals, generally the amount before breakfast is greater than the amount before dinner, and the amount before dinner is greater than the amount before lunch. The dosage before breakfast is generally greater than that before dinner, and before dinner is greater than that before lunch. The initial dose of most patients is small and needs to be gradually increased, generally adjusted once every 3-4 days, and each increase or decrease should be 2-4 U until the goal of blood glucose control is achieved. Thereafter, the dose adjustment interval should be extended and the adjustment range should be further reduced, and the insulin dose should be kept in a relatively stable and dynamic balance with diet and exercise. If the fasting blood sugar is high in the morning, after excluding the reactive hyperglycemia caused by nighttime hypoglycemia, the medium-acting dose before dinner should be increased; the short-acting dose before breakfast should be increased if the blood sugar is high after breakfast and/or before Chinese meal; the medium-acting dose before breakfast or the short-acting dose before lunch should be increased if the blood sugar control is unsatisfactory after Chinese meal or before dinner. Conversely, if the blood glucose is low at each of the above time signs, the insulin dose should be reduced at the corresponding time points. In addition, diabetic patients are affected by many living conditions that cause blood sugar fluctuations, and insulin dose should be changed at any time, such as banquets, sports, competitions, examinations, emotional stress, exertion, stress, infection, pregnancy, childbirth, surgery, trauma, etc. We should pay attention to adjust the dose and record the condition. Finally, we would like to remind patients that insulin dose adjustment involves many factors, and for different people and patients’ specific conditions, the goal of blood glucose control is different, and the insulin dosage is also different. Patients should closely monitor their blood glucose, keep close contact with their physicians, communicate with them in a timely manner, and adjust the insulin dose under the guidance of their physicians.