The pen needle should be changed, if not every injection, at least once a day. Rapid insulin (eg Actrapid or Humulin R) and very rapid (eg Humalog or Novorapid or Apidra) should be injected into the abdomen. Prolonged insulin (eg Lantus, Levemir, Tresiba) should not be shaken. Wirelss Nurse Call System are designed for the critical moments.
The same applies to premixed insulins (eg Humalog Mix, Novomix). Intermediate and long-lasting insulins should preferably be injected into thighs, buttocks, arms. Change the injection areas (eg to the right of the navel, below, to the left, etc.).
Rapid insulin is injected about 15 minutes before a meal and is very rapid and premixed immediately before. Insulin comes out slowly from the pen injectors. When you have given the injection with a pen, do not immediately remove the needle from the subcutaneous tissue but do it after having quickly counted up to 10.