Insulin injections are a daily necessity for many diabetic patients, but many patients have difficulty speaking clearly about the angle of needle entry and the method of pinching the skin, although they routinely lance the injections every day. In fact, insulin injection must pay attention to details because it is a job that is repeated every day, and only completely correct operation can mitigate the adverse consequences of long-term injections. After all, diabetes is a chronic disease, and only by being prepared for a long-term “war” can patients fight this “long war”. Patients should check the injection site before injection; if subcutaneous fatty growth (hard nodules), inflammation or infection is found at the injection site, the injection site should be changed; when injecting, attention should be paid to keeping the injection site clean; when the injection site is unclean or the patient is in an environment where infection can be easily spread (e.g., hospital or nursing home), extra attention should be paid to disinfecting the injection site. Pinch skin Before injection, patients should check the corresponding injection sites one by one to determine whether pinch skin injection and the angle of injection are necessary according to their body size, injection site and the length of the needle (the 4 mm or 5 mm ultra-fine ultra-short needles, which are currently recommended for widespread use, are almost painless during injection). All patients should learn the correct method of skin pinching at the beginning of insulin therapy: lift the skin with the thumb, index finger and middle finger, and do not pinch the skin too hard to cause white or painful skin; do not use the whole hand to lift and pinch the skin to avoid lifting the muscles and subcutaneous tissues together; the best steps for skin pinching injection are: (1) pinch the skin to form a skin fold; (2) enter the needle at 90° to the surface of the skin fold and slowly push insulin; (3) when the plunger is fully pushed to the bottom, push the needle to the bottom. ③ When the plunger is fully pushed to the bottom, the needle should stay in the skin for at least 10 seconds (using insulin pen injection); ④ pull out the needle; ⑤ release the skin fold. Angle of needle insertion To ensure that insulin is injected into the subcutaneous tissue, the injection can be performed at an angle of 45° without pinching the skin to increase the thickness of the subcutaneous tissue and reduce the risk of injection into the muscle layer. With shorter (4 mm or 5 mm) needles, pinching of the skin is not necessary in most patients and allows for 90° approach; with longer (≥ 8 mm) needles, pinching of the skin and/or 45° angle approach is required to reduce the risk of injecting insulin into the muscle. Needle retention time In clinical practice, it has been found that after the needle is withdrawn by injection using an insulin pen, the needle may leak, which reduces insulin utilization and thus affects the effectiveness of glycemic control. This is due to the fact that the needle of insulin pen is slimmer, and the time of drug injection into the body is relatively prolonged when pushing the drug, and with the increasing amount of injected dose, the rate of drug absorption at the original site where the needle tip is located after injection will slow down with the increase of dose. Extending the needle retention time can reduce the phenomenon of insulin leakage. Needle retention time is related to the characteristics of the injected dose and the length of the needle. The flow rate of the drug solution is also related to the inner diameter of the needle for injection pen, and the larger the inner diameter of the needle, the faster the flow rate of its drug solution. At present, there are needles with “thin-walled” design in the clinic, which are more conducive to the injection of drug solution and beneficial to the absorption of insulin by the body with a larger inner diameter in the case of the same outer diameter. Therefore, the needle should be held for at least 10 seconds when injecting with an insulin pen to ensure the drug dose and prevent leakage of the drug. It is recommended that needles for pen injections should be disposable and should be removed immediately after the injection is completed and discarded with the outer needle cap on, rather than being left in the insulin pen. This will prevent air (or other contaminants) from entering the refill or the spillage of the drug inside the refill, which in turn will affect the accuracy of the injected dose, help to control blood glucose smoothly, and ultimately reduce medical costs. Some studies have shown that multiple use of injection needles can cause blunting of the needle tip and loss of the lubricating layer on the needle surface, increasing patient pain and directly affecting patient compliance. The percentage of patients with poor glycemic control also increases significantly with the number of repeated needle uses. Repeated use of needles may lead to subcutaneous fat growth, large blood glucose fluctuations, blood glucose not easily reaching the standard, increased insulin dosage, and ultimately increased treatment costs, so injection needles are best used disposably.