This is especially true when using a perpendicular approach with a 12.7mm needle. The imaging studies suggest that intramuscular injections are virtually inevitable when perpendicular injections, without pinching up, are performed in the thigh. Most men have less than 8mm of subcutaneous tissue on the lateral thigh which is a common site of injection. If men inject without pinching up in this region, the insulin will almost invariably go into muscle. Patients who notice leakage from thigh injections with the short needle should be advised to use the abdomen as their primary injection site or should be switched back to longer needles.
Rotation allows complete healing of traumatized tissue.
It is just as important to rotate 1 or 2 cm up or down in one region as it is to rotate from region to region. Patients who rotate sites are less likely to develop the lumpy nodules known as lipohypertrophy. This increases injection pain, bleeding, bruising and possibly scarring. Needles that dull through reuse have a greater risk of breaking off and remaining embedded in the patient. Reuse of the needle also allows insulin crystals and platelet plugs to clog the barrel, leading to difficult or inadequate delivery of insulin.