To have diabetes means the need to administer insulin per injection several times a day or to change a pump catheter every second day. This can leave marks. Read here how damage to the subcutaneous fatty tissue can occur and how it can be avoided.

Children with diabetes are often dependent upon the regular administering of insulin. The insulin is either injected four times a day with a pen or administered continually via an insulin pump into the fatty layer which underlies the skin (subcutis). The areas used for the injections and the pumps are the subcutaneous layers of the abdomen, upper thighs, buttocks, and arms.

The Skin and its Function
The skin is an organ and fulfils many functions. It protects the body from chemicals and external trauma, and regulates temperature. It also processes sensory stimuli.
The human skin consists of different layers of which only the upper one is visible.

Skin Damage Due to Injections
When insulin is administered into the subcutaneous fatty layer, it can cause inflammation or even infection. For this reason, great care is taken in diabetes management courses to emphasize the need to regularly change the injection site. This, however, can present problems in small children: on the one hand, small children often have very little subcutaneous fat, especially in the abdominal area; on the other hand, the areas available for injections are often very small, leaving little room to change the injection sites.

Repeated puncturing in the same place can lead to irreparable damage to the tissue, whereby underlying fatty tissue can accumulate as well as disintegrate. Such alterations in the skin are known as lipodystrophy.

Accumulation of fatty tissue
Accumulation of fatty tissue is visible in the form of bulges under the skin surface. Occasionally, a hardening of the underlying tissue can be felt. The medical term for such a case is lipoma or lipohypertrophy.

Loss of fatty tissue
In contrast, a loss of fatty tissue results from the demise of the subcutaneous fat cells. The skin in these places becomes thinner. This condition is visible in the form of indentations. The medical term for this is lipoatrophy.

Insulin Less Effective
Why such changes occur in the skin is not yet totally clear. It is well known, however, that such cases are more common in children, and especially in girls, than in adults.

When injections are repeatedly administered in the same place, the resulting skin damage is not just purely cosmetic—it also impairs the efficacy of the insulin. Consequently, more insulin is needed to attain the same result which, in turn, can lead to an insulin overdose with subsequent hypoglycaemia.

Change the Injection Sites!
Lipohypertrophy and lipoatrophy can be avoided by consistently changing the injection site. However, despite the utmost care, some skin damage can still occur.

What is the Treatment?
Once skin damage does occur, the only means of therapy is to avoid injecting again in the affected area. Even so, it can take months until lipomas or lipoatrophy has subsided. In rare cases, they can remain permanently.

Infections and Wounds
Further types of skin damage that can result from repeated injections and use of insulin catheters are inflammation and purulent wounds (abscesses).
When a needle or a catheter is placed into the subcutaneous layer, it is as if a foreign object penetrates the skin. Although the needle is so fine that the tissue is only minimally irritated, every prick represents a minute injury that may allow for bacteria and germs to penetrate from the outside. The greatest risk is when germs, already present on the skin surface, enter the skin along with the needle.

Avoiding infection
The injection site must be kept thoroughly clean at all times to avoid infection. Also, needles should only be used once. Why? The lubricative surface of the needle is torn on the first use. If the needle is used again, microscopic hooks can form which can cause injury and infection.

With insulin pump therapy, it is important to carefully disinfect the area into which the catheter will be placed, and to exchange the catheter for a new one every 48 hours.

If inflammation or a pimple does happen to occur at the site, a physician must be consulted so that antibiotic treatment can be prescribed if necessary. If a larger purulent abscess develops, it may need to be treated surgically to relieve the infection.

Allergic Reactions
In very rare cases, allergic reactions can occur with the use of insulin. This manifests itself by redness at the point of injection. The redness is usually around 2–4 cm in diameter and itches, and subsides after four to five days. In extremely rare cases, a severe allergic reaction can occur with difficulty in breathing or even allergy shock.

The reason for an allergic reaction does not usually lie in the insulin itself. Insulin today is manufactured with such high hygienic precision that it cannot contain anything which could cause allergy. In most cases, it is one of the accompanying ingredients (eg, vehicle and preservatives) that causes the allergic reaction. Even the antiseptic used to disinfect the skin before the injection may cause a reaction.

In most cases, however, the symptoms subside within a short time and need no further treatment. However, if the reactions occur again, the type of antiseptic used to clean the area should be considered first and, if need, an allergy test carried out.

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Nicolin Datz, MD
Kinderkrankenhaus auf der Bult, Hannover
E-Mail: datz(at)hka(dot)de