Insulin Injection Sites

Insulin is a hormone that helps to regulate blood sugar. People with diabetes may need to inject insulin if their pancreas makes inadequate amounts or when they are unable to use their own insulin efficiently.

If you currently take insulin or are about to start, it's important to understand best practices for injecting insulin. Understanding insulin injection sites and the importance of site rotation may prevent skin damage.

Inject Into Fatty Tissue

Insulin is meant to be injected subcutaneously (under the skin) into fatty tissue, such as the abdomen, outer parts of thighs, backs of arms, and buttocks. Injecting insulin into fatty tissue helps the body to absorb insulin slowly and predictably.

This layer of tissue sits on top of the muscle and has few nerves, which can make injections more comfortable. The amount of fat thickness is variable based on injection site, age, gender, and weight.

Abdomen

The abdomen is a common insulin injection site for people with diabetes. The abdomen has a large surface area and less muscle than other sites, making it more comfortable and with space to rotate the specific location for your injection.

It is also easy to access, which makes it an easy and practical injection site. When injecting into the abdomen, you should avoid the belly button. Instead, inject insulin at least two finger lengths (or two inches) away from the belly button.

Young children, people who are very thin, or those who have very little body fat, may find the abdomen to be a difficult site to use because they can't pinch up a half-inch of fat.

Backs of Arms

If you inject into the upper arm, do not inject into the shoulder. Instead, use only the outer back area (where the most fat is). If you have difficulty pinching the upper arm yourself, you can prop your upper arm against a wall or door to access the fatty tissue. Or you may have someone else help you with your injections.

Upper Buttocks or "Love Handles"

The upper buttocks have the thickest layer of fat, but can be hard to inject and rotate without some assistance. The "love handles" (that area just above your hip), can be a good injection site for young children or very thin adults because you can usually squeeze fat in this area.

Outer Side of Thighs

If you are injecting into the thighs, use the outer, fattier part of the thigh and avoid the inner thighs. If you inject into your inner thigh and your thighs rub together when you walk, it can make the injection site sore.

It's best to use the upper thigh, as the fat layer thins out further down the leg. Avoid injecting close to the bony area above the knee.

Importance of Site Rotation

Injecting into the same exact spot on the same exact site over and over again can cause the skin to develop hard lumps or extra fat deposits. These lumps can be unpleasant looking, and they can change the way insulin is absorbed and make it more difficult to control your blood sugar.

Over time, the thickened skin may lose nerve endings and as a result, shots may become painless. A painless injection may seem like a good thing, but it can be a sign that the skin is becoming damaged.

The best way to control blood sugar is to aim to use the same site at the same time of day daily and to rotate within that site. For example, if you take mealtime insulin, inject it daily into your abdomen for breakfast, but rotate within that site daily. And if you take long-acting insulin at night, you can use your thigh, for example, but rotate within that site.

Best Place to Inject and Absorption

The best place to inject insulin will depend on what type of insulin you are using and when you are using it. Your body absorbs insulin differently depending on where it is injected. Typically, insulin absorption is fastest in the abdomen, somewhat slower in the upper arms, even slower in the thighs, and slowest in the buttocks.

Mealtime and Long-Acting Insulin

Usually, it is recommended to deliver mealtime injections in your abdomen, as they work fastest when you inject them. This helps to lower post-prandial (after meal) blood sugars.

And long-acting insulin, such as Lantus or Toujeo, can be injected into a slower absorption spot, such as the buttocks or upper thigh.

Exercise and Absorption Rate

If you plan to exercise after injecting insulin, avoid the area you are about to exert the most energy. For example, if you plan on doing a lower body workout, avoid using your thighs. Or if you are playing a game of tennis, avoid the arms.

Injecting into these active sites will increase the absorption rate and increase your risk of hypoglycemia, which is low blood sugar.

Tips for Choosing Sites

Fast insulin absorption is important to reduce after-meal blood sugars.

Therefore, you should inject your breakfast and lunch, and maybe dinner (depending on post-dinner sugars and activity level) bolus doses into your abdomen. Do this unless instructed otherwise by a healthcare provider, or if you have an increased risk of low blood sugar or reactive hypoglycemia,

It is not advised to inject your breakfast insulin in the abdomen one day and into the thigh the next day. If possible, be consistent within each site and rotate accordingly.

Long-acting or bedtime insulin could be injected into the thigh, buttocks, or upper arm so that the absorption can happen gradually, covering your insulin needs throughout the night.

Ultimately, what's most important is that you have access to a site and are consistent. The choice is always yours.

Reasons to Avoid a Particular Site

If you develop lumps and bumps at injection sites, avoid the area of the bump for several months because that area will absorb insulin differently and this can affect your blood sugar levels.

In addition, avoid using sites where you plan on exercising, as this can increase the risk of hypoglycemia due to increased absorption.

Lastly, avoid injecting into moles or scar tissue, as these can also affect insulin absorption.

How to Tell You Need to Start Rotating Sites

You'll know if you need to start rotating sites if your skin changes, you no longer feel the injections, and your blood sugars begin to rise.

Skin changes that can be caused by insulin injection:

• The skin may appear to develop a "grape-like" lump or bump, which is known as lipo or insulin hypertrophy. It may be caused over time by the natural effects of insulin (one of which is to cause fat to grow) or by reusing needles. To prevent further development of hypertrophy, rotate injection sites and don't reuse needles.
• If you see a dip in the skin that has a firm texture, you may have a condition called fat atrophy which typically occurs when using impure insulin.
• A hard lump can appear after using an injection site repeatedly. This condition, referred to as lipodystrophy, is considered a fat scar.
• A bruised area should be avoided until the bruise goes away.

If you have a lump under the skin immediately after an injection, it could be that you didn't get the needle all the way into your fat tissue and the insulin was injected just under the skin. You may need to practice your injection technique or possibly use a longer needle.

If you develop red, irritated lumps or a rash at the injection site, you should discuss this with a healthcare provider, as this can be a sign of infection. You may have to change sites while the infection is being treated and cleared up.

Tips for Keeping Track of Where You Injected Last Time

A great way to rotate sites and keep track of where you injected last is to set up a cycle. You can start from left to right or follow the pattern of a clock, giving yourself a 12-day cycle. Using a 12-day cycle gives sites time to recover before being used again. Make sure to move a few inches from your last site.

You may also want to download an insulin injection chart and make note of the areas you are using so that you can keep track and rotate accordingly.