Insulin injection sites are mostly chosen from areas with more subcutaneous fat and loose skin, such as the abdomen (avoiding the umbilicus and bladder), the front and outside of the arm, the front and outside of the thigh, and the upper 1/4 of the buttocks, and currently insulin injection pens are available with different needle lengths of 4, 5, 6, and 8mm. Different injection sites and different needle lengths sometimes involve having to “pinch the skin” to avoid injecting into the muscle. Children and adolescent patients should use needles that are 4, 5 or 6mm in length. Patients who are thin or choose to inject in the extremities, especially if a 5- or 6-mm needle is selected, need to pinch the skin to form a skin fold before injecting. Given the increased risk of intramuscular injections with long needles, the use of 8mm needles should be avoided in pediatric and adolescent patients. If only an 8 mm needle is available (as in patients currently using a syringe), the skin should be pinched and injected at 45°. Adult patients may pinch the skin when injecting in the extremities or in the abdomen where there is less fat, to prevent intramuscular injection, even when using 4mm and 5mm needles. When using a 6mm needle, the skin can be pinched or injected at a 45° angle. In adults, again, there is no medical evidence to recommend the use of needles longer than 8 mm. Patients using needles ≥8 mm in length should be injected by pinching the skin or at a 45° angle in order to avoid intramuscular injection. Prior to injection, the appropriate injection site should be examined individually to determine the need for a pinch skin injection and the angle of injection based on the patient’s body type, the injection site, and the length of the needle. When the presumed distance from the skin surface to the muscle is shorter than the length of the needle, pinching up the skin can make the subcutaneous tissue at the site deeper and can effectively improve the safety of the injection. The correct technique for pinching the skin is to lift the skin with the thumb, index finger and middle finger. If the entire hand is used to lift the skin, there is a risk of pinching the muscle and subcutaneous tissue together, resulting in intramuscular injection. All patients should master the correct method of skin pinching at the beginning of insulin therapy: (1) pinch the skin to form a skin fold; (2) enter the needle at 90° to the surface of the skin fold, and then slowly push the insulin injection as follows (3) When the plunger is fully pushed to the bottom, the needle is left in the skin for at least 10 seconds (using insulin pen injection); (4) Pull out the needle; (5) Release the skin fold.