Insulin Injection Sites And Precautions
Insulin should normally be given by subcutaneous injection. This means it should go into the fatty tissue under the skin and above the muscle. If it is injected into the skin or muscle it is usually painful and will be absorbed differently. Everyone's body is different and it is, therefore, important to use the length of needle and injection technique which suits you best.
Insulin can be injected anywhere there is subcutaneous fat. You are advised to use a large area of the body for injecting, and to rotate the sites to avoid developing fatty lumps or swelling.
Insulin is used more uniformly when injected into the abdomen, slightly slower in the arm and then the leg, and slowest when injected into the hip area. It does not matter if you use only one site, for example injections may always be given in the abdomen as long as the injections are given over a wide area both vertically and horizontally. What matters is that the same site should be used at the same time each day, and that a wide area of each part of the body should be used.
What is injection-site swelling, what is the cause?
These are the most common cause of injection-site swelling (technically known as lipohypertrophy). They occur because insulin (any type) stimulates the production of fatty tissue, and are produced by injecting too much insulin in one place.
Fatty lumps do not carry a normal supply of nerves and blood vessels and so are not red or painful. They can range in size from just visible to the size of a tennis ball. They can be in one place or several places, depending on where injections are given. Some people find injecting into a fatty lump painless and by continuing to do so, make the lump larger. Although it can happen to anyone who is repeatedly injecting in one place, some people are more prone to develop such lumps. Also, insulin is absorbed slowly and irregularly from fatty lumps and this can cause problems with control.
If lumps have already occurred, it is important to completely stop injecting in that area. If the area is avoided for a while, small lumps will disappear. Larger ones may get smaller, but will often not disappear altogether. It is much better to prevent lumps from forming in the first place.
What causes pain at injection sites?
Small, painful lumps occur at the time of injection if the injection is not deep enough. The small lump will gradually disappear over the next few hours or days. These are easily avoided by injecting under the skin. This can be achieved in a variety of ways:
Use a slightly longer needle, or inject vertically rather than at a 45-degree angle.
If you have very little subcutaneous fat it is better to pinch up the skin. This ensures that the needle goes deep enough to get through the skin, but not so deep that it penetrates muscle, which is also painful and alters the rate of insulin absorption.
Infection at injection sites is very rare, partly because insulin preparations are sterile and bacteria cannot easily grow in the solutions. Occasionally an infection does occur and can lead to an abscess. Infected lumps usually look red and feel hot and painful. A really large abscess can cause a fever and make a person ill.
To avoid infection, make sure the skin is clean, though there is no need to use any special preparation – ordinary soap and water are sufficient. It is no longer advised to swab the site with alcohol, as it tends to harden the skin. No one is ever advised officially to inject through clothes, but many people do and never get infections. It has been shown in several studies that is quite safe to re-use the same needle and syringe or needle and pen on many occasions.
This does not cause infections, but frequent use of a needle may damage the tissue. Syringes or pens and needles should, of course, never be used by more than one person. If an infection does occur it should be treated, and that area avoided for further injections until the infection has cleared.
Allergic reactions to insulin injections are usually due to chemicals injected with the insulin rather than the insulin itself. Now that insulin preparations are highly purified, allergic reactions are very rare. Sometimes people get a slightly raised, red, itchy lump at the site of an injection. This most commonly occurs when someone first starts on insulin and usually wears off after a couple of days.
As mentioned earlier, itchy lumps usually disappear spontaneously. If the itching is very troublesome, there are medications available which can treat this. Very rarely it may be necessary to change to a different insulin preparation.
What size needle and syringe should I use?
Needles are available in two lengths -5/16” (short), or1/2 ” (long). Most individuals use 5/16”, however, if you are overweight you may need to use the longer 1/2 ” needle to improve the absorption of insulin.
Needles are available in four gauges - 28, 29, 30, and 31. The higher the number the thinner the needle gauge. Syringes and needles are not available in all sizes. Insulin pen needles are available in 31 gauge with a short needle and 29 gauge with a long needle. Insulin syringes offer 30 gauge with a 5/16” needle and 29 gauge with a 1/2 ” needle.
Syringes are available in 3/10cc holding 30 units, 1/2 cc holding 50 units, and 1cc holding 100 units. You may choose your insulin syringe size based on the amount of insulin you inject.
Point to Remember
Fatty lumps, small painful lumps, and infections are largely preventable. Prevention is always better than a cure. The new, longer-acting Lantus (glargine) insulin may cause slight discomfort at the injection site.
|Last Modified : May 28, 2003.|
|Compiled and edited by Editorial Team and approved by Expert Panel of DiabetoValens.com|