Diabetes Forecast July 2004

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FOR TYPE 1/TYPE 2 Insulin Users

Tips For Site Rotation

When it comes to insulin, where you inject is just as important as how much and when.

By Terry Lumber, RN, CNS, CDE, BC-ADM

For years, people who inject insulin have been advised to "rotate" or change their injection sites regularly. That advice still stands, even though times have changed and some of the original reasons for doing so no longer hold.

Insulin has come a long way in 25 years. Up until human insulins were introduced in the early 1980s, insulin was derived from cows and pigs. It was important to switch injection sites at random to avoid a condition called lipoatrophy. Lipoatrophy is a thinning or pitting of the fat layer under the skin where repeated injections are given, and it's caused by an immune response to animal insulins, particularly insulins derived from cows. With today's more purified human insulins and analogs, lipoatrophy is not the problem that it once was, and random site selection is no longer recommended.

However, if you take insulin by injection, you should still move your injection sites around. But not randomly; instead, today's educators recommend an orderly and consistent method of site rotation. That's because repeated injections in the same site can cause fat to accumulate over a period of time.

Think of it as a callus: Your skin can become lumpy, bumpy, or thickened when you inject at the same site too often. This can cause your blood glucose levels to fluctuate because the accumulation of fat reduces and delays the absorption of insulin.

Using site rotation, you can avoid overusing your injection sites and keep your blood glucose in better control.

Each Site Is Different

Insulin should always be injected into subcutaneous fat, the fatty tissue that lies right under the skin and right above the layer of muscle. Although there is subcutaneous fat all over your body, it's important not to inject insulin too close to large blood vessels and nerves, so only certain sites will do. Insulin is absorbed the most quickly in the abdomen, followed by the outer part of your upper arms, then the outer parts of your thighs. It's absorbed the most slowly in the hips and buttocks. The long-acting insulin glargine (Lantus) is the exception to the rule. No significant difference in absorption between sites has been observed with insulin glargine. However, if you use insulin glargine, you should still rotate sites to avoid the accumulation of fat underneath your skin.

If you inject insulin into your abdomen, make sure the injection site is at least two inches away from your belly button. Do not inject insulin into your inner thigh because of the concentration of blood vessels and nerves in that area.

Things To Remember

Developing a site rotation plan is a team effort. Work with your diabetes educator or diabetes care provider to find the best site rotation plan for you. Your plan should be based on your insulin regimen, your body type, and your personal preferences.

Here are some things to keep in mind when discussing site rotation with your care provider.

The abdomen works. It's okay to use only your abdomen as long as you rotate your injection sites within the area. This method allows for the most consistent absorption.

Timing is everything. If you inject into more than one area, try to give your injections in the same area at the same time each day. For example, you can take your morning insulin in your abdomen and your afternoon or evening insulin in your thighs. This will also give you some consistency in absorption.

Different sites can be used for different insulins. Each site can be designated for a specific insulin. For example, you might take rapid-acting (pre-meal) insulin in your abdomen and long-acting insulin in your thighs or buttocks.

Distance matters. When rotating sites within one injection area, keep injections about an inch (or two fingerwidths) apart.

Exercise affects absorption. Massage or exercise that occurs around the time of the injection may speed up absorption because of increased circulation to the injection site. If you plan on strenuous physical activity shortly after injecting, don't inject your insulin in an area affected by the exercise. For example, if you plan to play tennis, don't inject into your racquet arm. If you plan to walk, jog, or run, don't inject into your thighs.

Temperature counts. The temperature outdoors or in a room can affect insulin absorption because it affects your circulation. Hot temperatures speed absorption because they increase circulation at the injection site. Cold temperatures have the opposite effect.

Damaged areas are off-limits. Do not inject into scar tissue or areas with broken blood vessels or varicose veins. Scar tissue may interfere with absorption. Avoid areas with varicose veins and broken blood vessels to avoid mistakenly injecting directly into a blood vessel. Insulin should always be injected into fatty tissue.

Consistency is key. Whatever site rotation you use, be consistent. Do not randomly inject your insulin from site to site (for example, from arm to thigh to abdomen).

A site rotation plan will help you avoid inconsistent insulin absorption and fluctuating blood glucose levels. Once you have devised a plan with your health care provider, keep track of how well it works. If it's not working as well as you would like, don't be afraid to call your health care team. Don't quit until you've found the system that works right for you.

Terry Lumber, RN, CNS, CDE, BC-ADM, is director of the Inova Diabetes Center in Fairfax, Va.

 

Injection Locator

The Injection Locator is a product that helps with site selection and rotation. It is made from vinyl and contains holes about one inch apart. You can write on it to keep track of injections. This may be useful for children trying to keep track of their site rotation plan, under the supervision of an adult. For more information, call 1-877-250-2020 or visit www.injectionlocator.com.