Be sure to follow your own doctor's instructions regarding the use of insulin.
What are the different types of insulin?
Several types of insulin are available. Each type starts to work at a different speed, known as “onset,” and its effects last a different length of time, known as “duration.” Most types of insulin reach a peak, which is when they have the strongest effect. Then the effects of the insulin wear off over the next few hours or so.
- Formulations: Lispro, aspart or glulisine
- How fast it starts to work (onset): About 15 minutes after injection
- When it peaks: 1 hour
- How long it lasts (duration): 2 to 4 hours
Regular (R) or Short-acting Insulin
- Formulations: Generic
- How fast it starts to work (onset): Within 30 minutes after injection
- When it peaks: 2 to 3 hours
- How long it lasts (duration): 3 to 6 hours
- Formulations: NPH (N), or Lente (L)
- How fast it starts to work (onset): Within 2 to 4 hours after injection
- When it peaks: 4 to 12 hours
- How long it lasts (duration): 12 to 18 hours
- Formulations: Ultralente (U)
- How fast it starts to work (onset): Several hours after injection
- When it peaks: Does not peak
- How long it lasts (duration): 24 hours; some last longer
Source: Insulin basics. American Diabetes Association
The chart above gives averages. Follow your doctor’s advice on when and how to take your insulin. Your doctor might also recommend premixed insulin, which is a mix of two types of insulin. Some types of insulin cost more than others, so talk with your doctor about your options if you're concerned about cost.
What are the different ways to take insulin?
The way you take insulin may depend on your lifestyle, insurance plan, and preferences. You may decide that needles are not for you and prefer a different method. Talk with your doctor about the options and which is best for you. Most people with diabetes use a needle and syringe, pen, or insulin pump. Inhalers, injection ports, and jet injectors are less common.
Needle and syringe
You’ll give yourself insulin shots using a needle and syringe. You will draw up your dose of insulin from the vial, or bottle, into the syringe. Insulin works fastest when you inject it in your belly, but you should rotate spots where you inject insulin. Other injection spots include your thigh, buttocks, or upper arm. Some people with diabetes who take insulin need two to four shots a day to reach their blood glucose targets. Others can take a single shot.
An insulin pen looks like a pen but has a needle for its point. Some insulin pens come filled with insulin and are disposable. Others have room for an insulin cartridge that you insert and then replace after use. Insulin pens cost more than needles and syringes but many people find them easier to use.
An insulin pump is a small machine that gives you small, steady doses of insulin throughout the day. You wear one type of pump outside your body on a belt or in a pocket or pouch. The insulin pump connects to a small plastic tube and a very small needle. You insert the needle under your skin and it stays in place for several days. Insulin then pumps from the machine through the tube into your body 24 hours a day. You also can give yourself doses of insulin through the pump at mealtimes. Another type of pump has no tubes and attaches directly to your skin, such as a self-adhesive pod.
Another way to take insulin is by breathing powdered insulin from an inhaler device into your mouth. The insulin goes into your lungs and moves quickly into your blood. Inhaled insulin is only for adults with type 1 or type 2 diabetes.
An injection port has a short tube that you insert into the tissue beneath your skin. On the skin’s surface, an adhesive patch or dressing holds the port in place. You inject insulin through the port with a needle and syringe or an insulin pen. The port stays in place for a few days, and then you replace the port. With an injection port, you no longer puncture your skin for each shot—only when you apply a new port.
This device sends a fine spray of insulin into the skin at high pressure instead of using a needle to deliver the insulin.
Categories of Insulin
Insulin has been available as a treatment for diabetes since 1922 and has saved countless lives. This life-saving hormone was originally derived from animals, but all forms of insulin available today in the U.S are synthesized in a laboratory.
There are many types of insulin. They vary depending on several characteristics, including:
- Onset. The length of time before the insulin reaches the bloodstream and begins lowering blood glucose levels
- Peaktime. The time during which the insulin exerts its maximal effects
- Duration. The length of time the insulin continues to lower blood glucose.
Insulin is also available in varying strengths measured in units. The most commonly used strength in U.S. is U-100, which means it has 100 units of insulin per milliliter of fluid. (U40 has 40 units of insulin per milliliter of fluid. It is still used in Europe and in Latin America. If you're traveling outside of the U.S., be certain to match your insulin strength with the correct size syringe.)
Selecting and Using Insulin
Your doctor will prescribe one or more types of insulin based on several factors. The most important factor is the blood sugar levels that are measured before and after meals, and at other times during the day. Other factors include the following:
- the use of other medications, such as oral diabetes medications.
- the presence of other medical conditions, such as pregnancy.
- lifestyle, such as an ability to maintain a predictable routine
- the use of previous insulin regimens and their ability to control glucose levels
Insulin is usually recommended for use 30 minutes before a meal if you take regular insulin alone or with a longer-acting insulin. If you take a rapid-acting insulin, you will probably be advised to take your insulin shot just before you eat.
Be sure to follow your own doctor's instructions regarding insulin.
How does insulin work?
After a meal, glucose molecules are absorbed into the bloodstream and carried to the cells, where they are used for energy. Insulin helps glucose enter cells and signals the body to store any extra glucose in the liver and muscles in a form called glycogen. Your body can use the stored glucose (glycogen) whenever it is needed for energy between meals.
Insulin lowers your blood glucose whether you eat or not. You should eat on time if you take insulin. Taking too much insulin, or not eating soon enough after administering insulin can lead to hypoglycemia.
Where is insulin injected?
You can inject insulin into several places on your body. Insulin injected near the stomach works fastest. Insulin injected into the thigh works slowest. Insulin injected into the arm works at medium speed. Ask your doctor or diabetes teacher to show you the right way to take insulin and in which parts of the body to inject it.
Does insulin work the same all the time?
After a short time, you will get to know when your insulin starts to work, when it works its hardest to lower blood glucose, and when it finishes working. You will learn to match your mealtimes and exercise times to the time when each insulin dose you take works in your body.
How quickly or slowly insulin works in your body depends on:
- Your own response
- The place on your body where you inject insulin
- The type and amount of exercise you do and the length of time between your shot and exercise
Reference: The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and the American Diabetes Association (ADA)
Last updated: February 3, 2017