What is insulin?

Insulin is a hormone in the body that helps to regulate your blood glucose (blood sugar) levels. The body’s process for managing glucose levels is complex, but it starts with breaking down your food into sugar. The sugar enters your bloodstream, which is why we refer to it as “blood sugar”.

Insulin communicates to the body that its cells can utilize the blood sugar for energy and that some blood sugar can be stored for later. When cells uptake blood sugar, insulin levels lower. These mechanisms become disrupted in diabetes, where too much blood sugar over time leads to insulin resistance, meaning the cells are not as receptive to insulin as they should be. If unmanaged, this causes dysregulation of blood sugar levels over extended periods, which can lead to several other complications. These include things like kidney damage, nerve damage, cardiovascular events, vision problems, and more.

You can treat diabetes by integrating proper exercise, diet, and medication into your daily routine. In terms of medication, you may take a pill, insulin, or a combination of the two. When taken correctly, insulin can be very effective in treating diabetes.

How does insulin help with diabetes?

When you take insulin, it works in the body the same way natural insulin does. It helps to maintain your blood sugar in an appropriate range.

What types of insulin are there?

Though insulin is incredibly effective in treating diabetes, there are several types of insulin, routes of administration, and directions that can make the treatment process confusing for patients.  The kind of insulin you use will depend on your personal health history, age, and additional factors. Your provider will help you decide which is the best for you.

First, let’s review the different types of insulin. The different kinds of insulin are categorized based on how fast they work and how long they stay in the body. They are as follows:

  • Rapid acting. Rapid-acting insulin has an onset of 15 minutes and lasts between two and four hours. Typically, you would take rapid-acting insulin immediately before eating. It is usually used in combination with long-acting insulin.
  • Regular or short-acting. Regular or short-acting insulin has an onset in 30 minutes and lasts between three to six hours. Typically, you would take this type of insulin 30 to 60 minutes before eating.
  • Intermediate acting. Intermediate-acting insulin has an onset of two to four hours and lasts 12 to 18 hours. This upkeeps your insulin requirements for half a day and is thus used with rapid or short-acting insulin.
  • Long-acting. Long-acting insulin has an onset of two hours and lasts for 24 hours. It maintains your insulin requirements for a full day and is used with rapid or short-acting insulin.
  • Ultra-long acting. Ultra-long-acting insulin has an onset of six hours and lasts for over 36 hours.
  • Premixed. Premixed insulin has an onset of five to 60 minutes and lasts 10 to 16 hours. You take it 10 to 30 minutes before breakfast and dinner, and it contains both short and intermediate-acting insulin.

These varying types of insulin are supplied under numerous brand names.

How is insulin supplied?

In addition to having different types of insulin, there are also several routes in which you can administer it. The most common routes include a syringe, insulin pen, and insulin pump. The details of these administration methods are below:

  • Insulin syringe. The insulin syringe is the most commonly used administration method. It involves a plastic disposable syringe attached to a fine needle. With this method, you draw up insulin into the syringe and inject it under the skin. We will discuss proper administration methods for this later in the article.
  • Insulin pen. Insulin pens can be either reusable or disposable devices that include an insulin cartridge. They also include a needle that is used to administer the insulin under the skin.
  • Insulin pumps. An insulin pump is a small device that automatically administers insulin under the skin. These can last for several years.
  • Infusion. Insulin infusions can be given intravenously, however, this is done only under medical supervision. Thus, this route is not used at home.

What are the strengths of insulin?

Later in this article, we will discuss how to administer an insulin injection. However, it is first important to understand how insulin dosages are named so that you can ensure you are delivering the appropriate dose of insulin. Additionally, the type of insulin you use will match the type of syringe you use.

Standard insulin has 100 units within one milliliter (mL). Thus, standard insulin is denoted as U-100. The majority of insulin syringes are enumerated to provide U-100 insulin, meaning each notch on a 1 mL syringe is equivalent to one unit of insulin.

However, other more concentrated forms of insulin also exist, including U-300 and U-500. Though specific syringes for these forms are available, you may use, for example, a U-100 syringe with U-500 insulin.

How do I prepare an insulin injection?

For those who have never administered an insulin injection before, this can be a daunting task. Navigating the needle, syringe, pen, and/or insulin can be confusing. Thus, in this section, we will discuss the proper way to deliver insulin.

The first step to administering insulin is to make sure it is at room temperature. Thus, if you store it in the refrigerator, make sure to leave it out for 30 minutes before injection. Do not leave insulin at room temperature for more than 28 days.

Start by gathering your supplies together, including your insulin, syringes, needles, alcohol wipes, and disposal containers. Then, wash your hands thoroughly with soap and water. Double-check you are using the correct type of insulin and that it has not expired. Inspect the insulin to ensure that there are no clumps. Some types of insulin, like intermediate-acting insulin, come cloudy. For this type of insulin, make sure to roll it in your hands to mix.

Remove the plastic cover from the insulin bottle and wipe the top with an alcohol wipe. Remove the cap of the needle and pull the plunger of the syringe back to the dose you want. Place the needle into the insulin bottle and then push the plunger. Turn the bottle upside down and then pull the plunger back to get the exact dose into the syringe. If there are bubbles in the syringe, tap the bottle to remove the bubbles. Then, remove the syringe from the bottle. You are now ready to inject.

The process for preparing an insulin injection will depend on if you are using one or two types of insulin. If you are using just one type of insulin, you will follow the above instructions. If you are using two types of insulin, you will repeat this step with the second type of insulin.

How do I administer an insulin injection?

You must rotate the sites in which you administer your insulin each time. It can be injected into various parts of the body, including the abdomen, thighs, buttocks, and upper arm. Do not inject your insulin in areas that are bruised, tender, lumpy, swollen, firm, or numb. Only inject into clean skin.

To inject your insulin, pinch the skin and insert the needle at a 45-degree angle. Push the needle into the skin, release the skin from your fingers, and inject the insulin gradually. Let sit for five seconds before removing the needle.

How do I use an insulin pen?

Using an insulin pen is similar, but there are a few differences. You will start by washing your hands and ensuring that the insulin is clear. If it is cloudy, roll the pen between your hands. Take the cap off the pen and use an alcohol wipe to wipe the rubber stopper. Add a new pen needle to the pen. Prime the insulin pen by removing air bubbles from the needle, and then adjust the pen to the dose of insulin you need. The pen should be inserted into the skin at a 90-degree angle with the needle entering entirely into the skin. Then, push the knob to release your dose and hold the pen there for six to ten seconds. Place the used needle into a sharps container.

What do I do with the insulin and insulin supplies afterward?

Put your used needle and syringe in a hard container. Be sure to keep this container closed and far from children and animals. Make sure not to reuse any syringes or needles.


If you are on insulin to help manage your diabetes, you must have a full understanding of your treatment. This includes knowing what type of insulin you are on, and most importantly, how to administer it correctly. There are several steps involved in an insulin injection, but with time and practice, you will become an expert.