Injection sites - choose carefully

The insulin must be injected into the subcutaneous fatty tissue.

Always inject the insulin into the fatty tissue between the upper layers of the skin and the muscle. Injecting into the subcutaneous fatty tissue results in the insulin being distributed and absorbed well. Inadvertently injecting into the epidermis or the muscle leads to insulin activity that is difficult to predict, and can therefore result in fluctuating blood sugar levels.

You can inject into the abdomen, upper thighs and buttocks

It is recommended that you inject insulin into the fatty tissue of the abdomen, buttocks, or the outer side or front of the upper thigh. Keep at least two fingers width (3 cm) away from the navel. Avoid injections into the upper arm or the inner side of the upper thigh as there is a risk that you might inject into a muscle.

Dangers of injecting into a muscle:

• the risk of hypos increases due to unexpectedly fast absorption (onset of effect)
• unexplained fluctuations in the blood sugar level
• pain/pressure during insulin delivery
• Note: intramuscular injection of some types of insulin has not been approved.

Dangers of injecting into the epidermis:

• insulin deficiency (hyperglycaemia) due to too little insulin being absorbed or to leakage of the insulin from the puncture site
• pain/stinging during injection
• skin irritation or bruising

The speed of insulin action varies

You should inject insulin at the same times every day and always in the same part of the body (but at different injection sites), so that you can estimate the insulin action more accurately. It is important to note that insulin absorption and action is quickest when injected into the abdomen, followed by the upper thigh and the buttocks.

Short-acting insulin is usually injected into the abdominal area to achieve a rapid effect.
Long-acting insulin is usually injected into the upper thigh or the buttocks because the duration of action is prolonged there.

The speed of insulin action is also increased by improving the blood flow at the injection site. This can be achieved by:

• massaging/rubbing the injection site
• sunbathing, being in a sauna or a hot bath
• injecting into the upper thigh and subsequent physical activity (e.g. walking, jogging, cycling)
• other influences/measures that lead to a locally increased blood flow

Injection sites must be changed at regular intervals

Change the injection site after each injection, if possible according to a fixed 'rotation principle'. The sites should be at least 3 cm away from each other to avoid tissue hardening (lipohypertrophy).

Avoid injection into altered tissue

The absorption and action of insulin is unpredictable when it is injected into hardened tissue or fatty deposits (lipohypertrophy), scar tissue, moles or bruises. You should definitely avoid injecting insulin into these sites.