A Guide to Long-Acting Insulin

Medically Reviewed By Alexandra Perez, PharmD, MBA, BCGP
Was this helpful?

Long-acting insulins are exactly what their name implies. They are injectable insulins that have a longer period of activity in the body than short- or intermediate-acting insulins. They can stabilize your blood sugar for longer periods of time, making diabetes easier to manage.

Read on to learn more about long-acting insulin.

What are the types of long-acting insulin?

a person is injecting insulin
Eddie Pearson/Stocksy United

The Food and Drug Administration (FDA) divides insulins into five different types. These are:

  • Rapid-acting: This begins to work within 15 minutes.
  • Short-acting: This begins to work within 30 minutes to an hour.
  • Intermediate-acting: This begins working in 2–4 hours, with peak effectiveness at around 6–8 hours after injection.
  • Long-acting: This begins working in 2–4 hours and can last up to 24 hours.
  • Premixed: This is a shorter-acting insulin and a longer-acting insulin mixed together.

Long-acting insulins can be beneficial in controlling blood sugar levels over an entire day. With these, you may need fewer injections to manage your blood sugar.

Maintaining healthy blood sugar levels can lead to fewer complications, which may otherwise include kidney failure, eye issues, and problems with circulation.

What are some brand names of long-acting insulin?

Long-acting insulin has several brand names, but the following three types are the most prevalent.

  • Generic name: Insulin glargine. Brand names include:
    • Basaglar KwikPen
    • Lantus
    • Lantus Solostar
    • Toujeo
    • Toujeo Max
  • Generic name: Insulin detemir. Brand names include:
  • Generic name: Insulin degludec. Brand names include:

Learn some statistics about insulin here.

Which long-acting insulin is right for you?

Selecting a long-acting insulin is a decision that you should make with your doctor. You should consider every part of your life, including:

  • your diabetes management
  • your general health
  • other conditions you may have
  • family support available to you
  • your economic circumstances

Cost effectiveness

Long-acting insulins may stabilize blood sugar levels over a day or more. They are also shown to lower the incidence of hypoglycemia episodes that may be more common with other types of insulin. Hospitalizations and emergency department visits may be avoidable, saving substantially on costs.

However, the cost of long-acting insulin may be passed to the patient, causing individual out-of-pocket costs to rise. According to the World Population Review, the United States currently has the highest insulin costs in the world. For people with limited financial resources, high costs may make it difficult to comply with their prescribed regimen.

Interactions with other drugs

All insulins have the potential to interact with other medications. It is important to consider all medications you are taking when choosing a long-acting insulin.

The medications that may interact with long-acting insulin include but are not limited to:

  • medications that increase the risk of hypoglycemia, including:
    • antidepressants, such as fluoxetine and monoamine oxidase inhibitors
    • certain medications for high blood pressure, such as glucagon-like peptide-1 (GLP-1) analogs
    • antibiotics, such as sulfonamides
    • salicylates, including aspirin
    • antidiabetic drugs, such as sulfonylureas and SGLT2s
  • medications that decrease the effect of long-acting insulins, such as:
    • atypical antipsychotic medications
    • corticosteroids
    • oral contraceptives
  • medications and substances that can increase or decrease the effect of long-acting insulins, such as:

Although the agents listed above may increase certain risks, those risks are likely not large enough for a healthcare professional to change the therapy. Instead, they will likely monitor and adjust the insulin as needed. Talk with your doctor before making any changes to your medication regimens.

Learn how insulin can help control diabetes here.

How do you administer long-acting insulin?

You can inject long-acting insulins using a needle and syringe or an insulin pen. Insulin should be injected into the subcutaneous tissue below the skin.

Insulin syringes in the U.S. are generally orange and have needles that are not detachable. They come in several sizes. The needles are very fine and have a coating that allows them to glide through the skin. Your clinician will show you how to prepare and inject your insulin dose. You should rotate injection sites to prevent irritation from always using a single site, but you should generally stick to the same area of the body.

The abdomen is the most common site for insulin administration. However, clinicians may use other sites, such as the back of the arm and the side of the thigh.

Insulin pens come prefilled with insulin and generally have a small rotating wheel with a gauge that shows the number of units. Turn the wheel to the prescribed dose, install a new pen needle, and inject the medication.

Reusing syringes

The American Diabetes Association states that it may be possible to reuse insulin syringes to save money. However, you should only do this with guidance from your doctor. If you choose to reuse syringes, keep them capped between uses and avoid letting the needle touch anything except your skin and the insulin vial.

Do not reuse syringes if you have an active infection or an increased risk of infections.


Never share insulin needles with another person. This could transmit bloodborne pathogens.

Never drink insulin.

You can store insulin at room temperature for about a month. Injecting cold insulin may increase pain. Only store the vial that you are actively using at room temperature. Unopened vials and pens should be refrigerated.

Always check the expiration dates on insulin as well as on syringes. Do not use any expired products.

Dispose of used needles in a hard-sided container, such as a sharps container, laundry detergent bottle, or metal coffee can. Keep sharps out of reach of other people and pets.

Visually inspect your insulin before use to check for cloudiness or crystals that should not be there.

Never shake insulin vials. Gently roll them between your hands to mix them before preparing your injections.

Learn some tips for starting mealtime insulin here.

What are the side effects of long-acting insulin?

Be aware of the possible side effects that long-acting insulin can have.

Hypoglycemia, or low blood sugar

Hypoglycemia is the most common side effect of insulin therapy, and it can be one of the most dangerous. If your blood sugar level drops too low, it can cause unconsciousness or even death.

Every person with diabetes should understand the symptoms of hypoglycemia and how to treat them. Caregivers and support people also need to know these symptoms. They include:

Later symptoms may include seizures, unconsciousness, or unresponsiveness.

If you have any of these symptoms, check your blood sugar level. If you are unable to check your blood sugar, treat for hypoglycemia with a 15-gram serving of glucose in the form of glucose gel, hard candy, or juice.

Some symptoms of low blood sugar are similar to those of high blood sugar. However, because hypoglycemia is acutely dangerous, it is best to treat for it with an intake of glucose.

Allergic reactions

Allergic reactions have occurred with long-acting insulin use. These can range from local itching to severe anaphylaxis and death.

If you notice allergic symptoms when using a long-acting insulin, contact a doctor immediately.

Injection site reactions

Any injection can cause a local reaction, which may include irritation, flushing, or soreness at the injection site.

One way to minimize these reactions is to avoid using the same injection site multiple times. Instead, try to rotate sites within a single part of the body, such as the abdomen.

Weight gain

Weight gain is common with insulin therapy. One possible reason for this is that people with diabetes may treat hypoglycemic episodes with too many servings of sugar.

Another reason for weight gain involves the use of insulin directly.

Insulin provides more blood sugar, which is the body’s energy source, to the muscles and tissue for use. The body stores any extra sugar, or energy, as fat. If the sugar is not able to make it to the tissue or muscles, the body will not use it or store it.

When people take insulin, they are moving the sugar from the bloodstream to the tissue, and, again, their body will store any extra energy as fat.

You should monitor your weight and report any significant changes to your doctor.

Cardiovascular disease

Multiple studies have linked diabetes with cardiovascular disease, and insulin use may increase this risk.

However, one study of over 12,500 people showed no increase in cardiovascular issues with the use of insulin glargine. Increases in mortality have occurred with glycosylated hemoglobin (HbA1C) targets that were too low.

Your doctor will help you set some goals.


Long-acting insulins can be beneficial in stabilizing blood glucose levels over a 24-hour period. They can also improve quality of life by reducing hypoglycemic episodes and lowering the number of daily injections required.

Work closely with your doctor and follow instructions carefully. Keep a log or use a phone application that stores data about your diabetes management. Report any problems you may have and keep all appointments for lab work. Know your particular goals for blood sugar ranges and glycosylated hemoglobin levels. Finally, store and administer your insulin correctly.

Maintaining good health with diabetes is possible with teamwork and careful monitoring, and long-acting insulin is a useful and effective tool.

Was this helpful?
Medical Reviewer: Alexandra Perez, PharmD, MBA, BCGP
Last Review Date: 2022 Jul 29
View All Diabetes Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.