Insulin is a hormone that helps the body manage blood sugar when a person injects it. Suitable insulin injection sites can include a person’s abdomen, thighs, upper arm, and buttocks.

Some people with diabetes may need to take insulin via injection every day. A person cannot take insulin as a pill or oral medication. This is because enzymes in the stomach would break down the insulin before it reaches the bloodstream.

People use insulin injections to treat and manage diabetes alongside dietary and lifestyle changes and oral medications.

For people who require insulin injections, different types of insulin are available. In this article, we explain how to follow the doctor’s instructions on how and where to inject insulin.

A person needs to inject insulin into the layer of fat directly under the skin, known as subcutaneous tissue. An individual does this with a small needle or a device that looks like a pen. This is known as a subcutaneous injection.

It is important to inject insulin into fatty tissue because it absorbs consistently in fat. It is important not to inject too deep into muscle or an unsuitable area with little fat. This is because muscle can absorb insulin rapidly, which may cause it to work too quickly.

Several different sites can support an insulin injection. These include:


The abdomen is a common site that many people with diabetes choose for insulin injections. It is easy to access and often less painful than other sites due to protection by fat, greater surface area, and less muscle.

To give an injection into the abdomen, pinch a section of fatty abdominal tissue with fingers on either side.

The site should be between the waist and the hip bones, about 2 inches away from the belly button.

Avoid injecting near any scar tissue on the abdomen.


The front and side of the thigh are simple areas for self-injection.

When choosing the thigh as an injection site, insert the needle into the front of the thigh, halfway between the knee and the hip. It should be slightly off-center toward the outside of the leg. It is advisable to avoid the inner thigh due to the denser network of blood vessels in that area.

Though easy to access, regular injections in the thigh can sometimes cause discomfort when walking or running afterward.

Hips or buttocks

Another potential site for administering an insulin injection is the buttocks or hips.

To administer an injection here, draw an imaginary line across the top of the buttocks between the hips. Place the needle above this line but below the waist, about halfway between the spine and the side.

This site can be very difficult to use for self-injection and may require another person for administration. When injecting into the buttocks, avoid the lower part.

Upper Arms

The upper arm is another possible site for insulin injection. A person can place the needle into the tricep area at the back of the arm, about halfway between the elbow and the shoulder.

Difficult self-administration is the main disadvantage of this site. Getting enough of a pinch to administer the insulin can be tricky. Additionally, some healthcare professionals may advise against injections in the arms due to the higher risk of injecting into the muscle.

The body absorbs insulin at different speeds from each of the sites. This information can be useful when planning insulin injections:

  • Abdomen: Insulin enters the bloodstream most quickly after an abdominal injection.
  • Upper arms: The body absorbs insulin at moderate speed but slower than an injection in the abdomen.
  • Thighs: Insulin enters the bloodstream less quickly than the abdomen or arms.
  • Buttocks: Insulin enters the bloodstream most slowly from this site.

As such, administering rapid-acting insulin into the abdomen right after a meal will provide the fastest results.

It is also important to consider different types of insulin and how rapidly each type takes effect. Some insulin works within 15 minutes and lasts 2 hours, while longer-lasting insulin has an onset of a few hours and can last more than a day.

If a person uses different types of insulin, it is advisable to have separate injection sites. For example, a person may consider using a quick-acting insulin in the abdomen and injecting a long-acting insulin in the buttocks.

Exercise can increase the absorption rate of insulin. If an individual is participating in a workout or physical activity, it is necessary to account for this when planning injections.

For example, a baseball pitcher should avoid injecting into their throwing arm. It is also advisable for a person to wait at least 45 minutes after the injection to exercise a part of the body that is near the injection site.

It is important to avoid injecting into the same site over and over. This can irritate the skin and underlying fatty tissue.

If this happens, it may increase discomfort and cause complications. Puncturing the same point every time can lead to hard lumps or fatty deposits developing. These lumps are known as lipohypertrophy. This can be uncomfortable and even reduce the body’s effectiveness in absorbing the medication.

When rotating injections, move around within the area to ensure that the injection does not always take place in exactly the same spot. Usually, it is advisable to ensure injection sites are at least 1 centimeter (cm), or half an inch, away from each other.

For example, when taking a nighttime dose of long-acting insulin, a person might feel more comfortable injecting it into the thigh. However, they should switch between the right and left thigh each night.

If a person always administers a morning dose of rapid-acting insulin into their abdomen, they should alternate between different areas of the abdomen to avoid repeated injections into the same site.

To help manage diabetes and keep blood sugars within a suitable range, it is important for a person to regularly monitor their blood sugar levels. By monitoring levels, a person can administer insulin or consume carbohydrates when necessary.

Some people may choose to use a continuous glucose monitor (CGM) to help them monitor their blood sugar levels. A CGM is a wearable device that constantly measures a person’s blood glucose levels throughout the day and night.

If a person experiences any difficulty keeping their blood sugars within a suitable range, they can consult their doctor for advice.

Some frequently asked questions about insulin injection sites may include:

What are the 4 major sites for insulin injection?

The most common injection sites suitable for an insulin injection include the abdomen, thighs, upper arms, lower back, hips, or buttocks.

Where should insulin not be injected?

A person should not inject into muscle. This is because an injection into the muscle can cause insulin to work too quickly. Therefore, it is important to inject into areas of skin with subcutaneous tissue, such as the abdomen and thighs.

Should you pinch the skin when injecting insulin?

Depending on a person’s body type, the injection site, and the type of needle, some people may need to pinch the skin when injecting insulin. This is to ensure a person is injecting into fat and not muscle. If unsure, a person can consult their physician or a member of their diabetes healthcare team.

Read on to learn more about injecting insulin.

Which is the site with the fastest rate of insulin absorption?

Usually, the abdomen is the injection site that absorbs insulin the fastest. The next fastest is the arm, then the thighs, then the buttocks.

A person can administer insulin injections into the abdomen, upper arm, thigh, lower back, hips, or buttocks.

These sites work best as they contain subcutaneous tissue. This refers to a layer of fat below the skin. Insulin works best and most consistently when a person injects it into fatty tissue. As it is important to avoid injecting into muscle, some people may need to pinch their skin when injecting insulin.

Each site delivers insulin to the bloodstream at different speeds, with the abdomen being the fastest site. As such, it is important to consider the absorption speed of different sites depending on the time of day, how fast the body needs insulin, and the type of insulin.

Additionally, it is important to avoid repeatedly administering injections to the same spot. A person can contact their doctor for advice on switching injection sites and self-administering insulin.