How to inject insulin properly

• To inject insulin properly, you need to put it into the fat layer under the skin.
• The most effective way to inject insulin is through the abdomen, though you should slightly change your location every day.
• You should also make sure to hold the injection at the right angle — either 90 degrees or 45 degrees, depending on your doctor's advice — and leave the syringe in your skin for 5 seconds.
• This article was reviewed by Jason R. McKnight, MD, MS, a family-medicine physician and clinical assistant professor at Texas A&M College of Medicine.

About 24% of people with diabetes are treated with insulin. However, insulin cannot be taken as a pill because it would be broken down during the digestive process. Instead, it must be delivered into the tissues under the skin. This is most commonly done using insulin injections.

Here's what you need to know about using insulin and how to inject it properly.

What is insulin?

Insulin is a hormone produced in the pancreas that signals your cells to absorb glucose, reducing your blood sugar.

People with type 1 diabetes do not produce insulin, so they must take insulin daily. People with type 2 diabetes are able to produce insulin, but their body can not utilize it efficiently, so they sometimes need to take injectable insulin. In both cases, insulin injections are a highly effective treatment for diabetes.

Where to inject insulin

Insulin should be injected into the abdomen, says Emory Hsu, MD, an endocrinologist at Santa Clara Valley Medical Center. That's because the insulin is absorbed most quickly into your bloodstream when it's injected into the skin your abdomen. The abdomen also gives you the largest area to work with, compared with injection sites in the arms and legs.

"Insulin is absorbed into the blood fastest from the abdomen, a little slower from the arms, even more slowly from the legs, and slowest from the buttocks," Hsu says. "When insulin is injected into sites like arms and legs, more blood sugar variation occurs, especially when these muscles are involved in exercise."

In addition, it's important to change your injection site each day to avoid lipohypertrophy, a condition where the tissue beneath your skin can harden because insulin is injected there too often.

Hsu recommends using the following guidance when selecting a spot to inject insulin:

• Choose a general area of your body, like the right side of your lower belly.
• Use this area for 1 to 2 weeks, moving your needle to a slightly different spot each time you inject insulin.
• After a week or two, start in another general area, like the left side of your lower belly, to give your skin time to heal.
• Don't inject insulin into moles, bruises, scars, wounds or within two inches of the belly button, Hsu says, because the skin in these areas is tough and can interfere with insulin absorption.

How to inject insulin

Your clinician will give you detailed guidance on how to inject insulin. It should be noted that there are a few different types of devices for taking insulin, so your exact procedure may vary. For many people, the process looks like this:

Get ready

1. Remove insulin from the refrigerator 30 minutes before injection. Most types of insulin should be stored cold, so many people keep it in the fridge. Talk to your doctor about what's best for the insulin that you're prescribed. Injecting cold insulin can make the injection more painful. Instead, aim for room temperature.
2. Gather supplies while the insulin warms to room temperature. You'll need insulin, syringes, alcohol wipes, and a sharps container for disposing of used syringes.
3. Get clean. Wash your hands with soap and water for at least 20 seconds.
4. Inspect the insulin. Check the expiration date and dosage (U-100 is most common). Ensure that there are no clumps in the bottle, which can indicate that the insulin has gone bad. If there are clumps, throw it away and get another bottle.
5. Prepare the insulin. If you're using an intermediate-acting insulin like Humulin N or ReliOn/NovoLIN N it will need to be rolled between your hands — not shaken — to mix it. This type of insulin looks cloudy. Most insulin appears clear and does not need to be mixed.

Prepare your dose

1. Uncover the insulin. Wipe the top of the bottle with an alcoholic wipe so remove any germs. Allow it to dry, but don't blow on it, since doing so can introduce germs.
2. Take the cap off the syringe. Be careful not to let the needle touch anything, so that it doesn't pick up any germs.
3. Get your syringe ready. Pull the plunger back so that the amount of air in the syringe is equal to the amount of insulin you need to take.
4. Insert the needle into the bottle. As you do this, push the plunger down and turn the bottle upside down, so that the correct dose of insulin fills your syringe.
5. Check for bubbles in the syringe. If you find any, tap the syringe so that they rise to the top. Move the plunger up to get rid of the air that's now at the top, and then pull it back down until you have the necessary dose of insulin in the syringe, with no air bubbles.
6. Put the insulin and syringe down. Carefully ensure that the needle doesn't touch anything, so that it stays clean. Placing it on a clean paper towel or cloth can help keep it clean.

Administer the injection

1. Choose an injection site. Make sure the site is at least two inches from your belly button and one inch from any scars.
2. Look at the site to make sure it's clean and dry. If it's dirty, wash it with soap and water. Do not use an alcohol wipe.
3. Pinch your skin so that a fold of skin is between your fingers.
4. Insert the needle at the angle your medical professional told you to use. For most people, this will be a 90-degree angle, with the needle going directly into the skin. Some people, especially those who are thin, will be told to use a 45-degree angle. If you notice a bump after injecting insulin, talk to your doctor or nurse about changing the angle.
5. Push the needle all the way into the skin, let go of the pinch on your skin, and slowly push the plunger until all the insulin is out of the syringe.
6. Leave the syringe in place for about five seconds to ensure that all the medication is delivered.
7. Remove the syringe at the same angle you inserted it, and set it down.

Dispose of the syringe

After injecting your insulin, you should put the used syringe in a sharps disposal container. These hard boxes will keep anyone else from being pricked by the used needles.

While a sharps container is always best, you could also use a hard container with a permanent top, like a laundry detergent container. Don't throw the sharps box into the trash. Rather, when it's almost full, make a plan for proper disposal. Some pharmacies and doctors offices have drop boxes for used sharps containers.

Takeaways

For most people, injecting insulin is easy after their doctor or nurse walks them through the process, Hsu says.

"If a patient is having difficulty injecting insulin on their own, they should let their diabetes educator or primary care provider know and have an open discussion on what can be done to assist them," he says.

To avoid common mistakes, make sure that you always do the following, says Hsu:

• Measure insulin from the top of the plunger, not the bottom
• Inject room temperature insulin
• Avoid the two inches around your belly button
• Change your injection site daily
• Do not clean skin or needle with alcohol

While insulin is generally a safe medication, people using it can experience low blood sugar, or hypoglycemia, if they don't have a good match between their insulin dose and their food intake.

Just in case, Hsu recommends always carrying a source of fast-acting sugar, like glucose tablets or a high-carbohydrate snack, when you're out of the house.

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