1, types of insulin According to the source can be divided into animal insulin (bovine insulin, porcine insulin), human insulin and insulin analogues. According to the duration of action can be divided into rapid-acting human insulin analogues, ordinary (short-acting) insulin, medium-acting insulin, long-acting insulin, long-acting human insulin analogues and premixed insulin of various ratios. 2. Site and time of insulin injection Normally, we should inject insulin into the subcutaneous tissue (below the dermis and above the muscle). Injecting too deeply (to the muscle layer) will speed up the absorption of insulin, increase the risk of hypoglycemia, and also increase the pain. The correct way to inject is to first pinch up the skin with your thumb, index finger or middle finger and then inject quickly with an insulin syringe or a regular type of pen needle. Injection sites: The most suitable sites for insulin injection in the human body are the abdomen, outer thighs, outer 1/4 of the arm and buttocks. On the other hand, there is a layer of subcutaneous adipose tissue under these tissues that can absorb insulin, so that insulin can be absorbed effectively and lower blood sugar. Among these sites, the abdomen is the preferred choice for insulin injection, mainly because the subcutaneous tissue of the abdomen is thicker, which can reduce the risk of injecting into the muscle layer and the abdomen absorbs insulin the fastest, and it is easiest for patients to pinch up the skin when injecting themselves. Precautions: 1. When injecting in the abdomen, it should be noted that the distance of one fist around the umbilicus should not be injected, but within the distance of one palm on both sides of 3-5 cm from the navel. 2, change the injection site, should not be injected in the same site several times in a row, each injection with the last injection site to maintain a distance of 3 to 4 cm, and often observe the injection site for hard knots, epidermal depression, pain or skin color changes. 3, storage of insulin Unopened insulin can be stored in the refrigerator between 2 ℃ and 8 ℃, valid for 1 to 2 years, after the expiration date, the efficacy of the drug is reduced; avoid freezing, because insulin is prone to deterioration and loss of activity after freezing. The insulin being used should be kept in a refrigerator at 2℃, and should be discarded if its efficacy is weakened for more than 1 month. When traveling, insulin can be kept in a special low-temperature bag and carried with you to avoid direct sunlight; avoid strong vibrations and bumps. Because strong light and repeated shaking may make insulin denatured and ineffective. How can we tell if insulin is not working? You can check the appearance of insulin solution before each injection. Under normal circumstances, rapid-acting and short-acting insulins are colorless and clarified solutions, once cloudy or the liquid turns yellow, they cannot be used; medium- and long-acting insulins or premixed insulins are generally in a uniform mist, once lumpy precipitates appear and cannot be shaken well, they fail and cannot be used. Insulin that has passed its shelf life should not be used. 4, insulin adverse reactions (1) hypoglycemic reactions: early symptoms include: hunger, dizziness, weakness, sweating, palpitations, hand trembling, pale face, etc.; later, irritability, disorientation, incoherence; if not treated in time, convulsions, seizures, coma, and even death. The possible reasons are too large dose of insulin; not eating on time or not eating enough after insulin injection; too much temporary physical activity, etc. (2) Allergic reaction to insulin: maculopapular rash, itching, generalized urticaria and anaphylactic purpura appear in and around the injection site, and anaphylactic shock may occur in very few cases. This kind of reaction is less common. It is mainly due to the impure quality of insulin preparation. (3) Subcutaneous fat malnutrition: Patients with long-term insulin injection often see atrophy or hyperplasia of subcutaneous tissue at the injection site, which leads to unstable insulin absorption and poor glycemic control. (4) Weight gain: Most of the patients show weight gain after insulin injection, at this time, they should strictly control their diet and exercise appropriately to reduce their weight. (5) Blurred vision: Blurred vision often occurs when the patient’s blood glucose drops rapidly, which is mainly due to the drop in blood glucose affects the osmotic pressure in the lens and the vitreous, so that the water in the lens escapes and refraction decreases, resulting in hyperopia. Generally, it does not need to be treated, and it will quickly return to normal with the blood glucose concentration.