If you have type 1 or type 2 diabetes, you may have heard about the prescription drugs Tresiba (insulin degludec) and Lantus (insulin glargine) from your doctor.

Tresiba and Lantus are both long-acting insulins used to manage blood sugar levels in people with type 1 or type 2 diabetes. (For more information on each’s drug uses, see the “What are Tresiba and Lantus used for?” section below.)

Tresiba and Lantus have some differences, too. Keep reading to learn how these drugs compare. And for more information, see the in-depth articles on Tresiba and Lantus.

Tresiba’s active drug is insulin degludec. Lantus’s active drug is insulin glargine.

Both active drugs are long-acting insulins. This means they work over time to keep your blood sugar levels steady throughout the day, in between meals, and during the night. Tresiba works for up to 42 hours, and Lantus works for up to 24 hours.

Tresiba and Lantus are both prescribed to help people with diabetes manage their blood sugar levels. The lists below give details on the uses of each drug.

  • Tresiba and Lantus are both used to:
    • manage blood sugar levels in adults with type 1 or type 2 diabetes
  • Tresiba is also used to:
    • manage blood sugar levels in children ages 1 year and older with type 1 or type 2 diabetes
  • Lantus is also used to:
    • manage blood sugar levels in children ages 6 years and older with type 1 diabetes

Note: Tresiba and Lantus aren’t approved to treat diabetes ketoacidosis (DKA). This is a serious, life threatening complication of diabetes. If you have questions about DKA, talk with your doctor.

Tresiba and Lantus both come as liquid solutions that are available in the following forms:

  • Vials. With the vials, you use a new syringe and needle for each dose.
  • Prefilled pens. The solution is already inside these pens. You use a new needle for each dose. You discard the pen once the doses are used up (or the insulin expires, whichever happens first). The Tresiba prefilled pens are called FlexTouch, and the Lantus pens are called SoloStar.

Both drugs are given by subcutaneous injection (an injection under your skin). And they’re both typically used once per day.

However, your dosage (number of insulin units used) will depend on your diabetes treatment plan and other factors, such as your:

  • type of diabetes
  • age
  • weight
  • current insulin regimen, or whether you’re new to insulin

The short answer: Yes, you can switch from using one of these drugs to the other.

Details: You can switch between Tresiba and Lantus as your long-acting insulin. However, changing your insulin regimen may raise your risk for hypoglycemia (low blood sugar) or hyperglycemia (high blood sugar).

Hypoglycemia or hyperglycemia can occur if you change any part of your insulin regimen, including:

  • insulin strength
  • the type or manufacturer of the insulin
  • the injection site or how you administer your doses

If your doctor approves the switch from one drug to another, they’ll monitor you closely until you’re stable on the new drug. If you have type 2 diabetes, your doctor may need to adjust your dosage of any diabetes drugs you take by mouth.

Your doctor will prescribe your new dosage based on several factors. But in general:

  • When switching from Tresiba to Lantus, your current long-acting insulin dose (number of insulin units) may need to be adjusted.
  • When switching from Lantus to Tresiba, your new dose (number of insulin units) will be the same as your current long-acting insulin dose.

Reminder: You shouldn’t switch drugs or stop your current diabetes treatment unless your doctor recommends it. If you’re interested in making a change, talk with your doctor.

Like all drugs, Tresiba and Lantus may cause side effects. These drugs are both long-acting insulins, so their side effects are similar.

The sections below list some side effects that are possible with these drugs. And for more information about possible side effects, see these in-depth articles on Tresiba and Lantus.

Mild side effects

Tresiba and Lantus may cause mild side effects in some people. The chart below lists examples of mild side effects that can occur with these drugs. Most of these side effects are mild or may be easily managed.

TresibaLantus
Weight gainXX
Hypoglycemia (low blood sugar)XX
Upper respiratory infections (such as the common cold)XX
HeadacheXX
Reactions at the injection site*XX
Flu-like symptoms (chills, fever, vomiting, belly cramps)XX
Lipodystrophy (changes in skin thickness near the injection site)XX
Swelling in your legs, ankles, or feetXX
DiarrheaXX
Skin rash or itchy skinX

* Injection-site reactions may include skin that’s red, swollen, itchy, painful, or tender in the area where you’ve injected the medication.

This chart may not include all mild side effects of these drugs. For more information on mild side effects of the two drugs, see the prescribing information for Tresiba and Lantus.

Serious side effects

In addition to the mild side effects described above, serious side effects may occur in people using Tresiba or Lantus. In general, serious side effects from these drugs are rare.

See the chart below for a list of possible serious side effects.

TresibaLantus
Hypokalemia (low potassium levels)XX
Severe hypoglycemia (low blood sugar)XX
Severe allergic reactionXX

If you’re concerned about serious side effects, talk with your doctor about your risk for side effects with either drug.

Whether you have health insurance or not, cost may be a factor when you’re considering these drugs. To see cost estimates for Tresiba and Lantus based on where you live, visit GoodRx.com. But keep in mind that what you’ll pay for either drug will depend on your treatment plan, health insurance, and the pharmacy you use.

Tresiba and Lantus are both brand-name medications. There isn’t currently a generic version of either drug. (A generic drug is an exact copy of the active drug in a brand-name medication that’s made from chemicals.)

Lantus is a biologic medication, which means it’s made from living cells. Although there isn’t a generic form of Lantus, there’s a “follow-on” insulin glargine drug available called Basaglar. Follow-on insulins are biologic drugs that are very similar to the original brand-name drug. Basaglar is made with the same type of insulin as Lantus.

However, follow-ons aren’t considered true generic drugs. This is because the way biologic drugs are made is very complex, and true copies of the original drug can’t be made.

You’ll usually pay more for the original brand-name drugs than for generics or follow-on drugs.

If you‘re interested in using Basaglar instead of Lantus, talk with your doctor.

Tresiba and Lantus are both prescribed to help people with type 1 or type 2 diabetes manage their blood sugar. The American Diabetes Association’s guidelines recommend both drugs as treatment options for certain people with either type of diabetes.

In addition, a review of studies found that both Tresiba and insulin glargine (the type of insulin in Lantus) were equally effective at improving blood sugar levels in adults and children with type 1 or type 2 diabetes.

However, some research suggests that Tresiba may be more effective than Lantus at preventing hypoglycemia (low blood sugar) during the night. This may be the case for people with either type of diabetes.

Talk with your doctor about which long-acting insulin is right for your diabetes treatment plan. And if you’d like to learn more about how these drugs performed in certain studies, see the prescribing information for Tresiba and Lantus.

Tresiba or Lantus may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take either drug.

Before using Tresiba or Lantus, talk with your doctor if you have any of the following conditions or health factors.

This list may not include all warnings for these medications. To learn more about the drugs and their warnings, see these in-depth articles for Tresiba and Lantus.

If you have type 1 or type 2 diabetes, Tresiba or Lantus may help you manage your blood sugar levels. They’re both long-acting insulins that come in similar forms, are administered the same way, and have similar side effects.

However, one difference between these drugs is how long they work to manage your blood sugar levels. Tresiba works for up to 42 hours, and Lantus works for up to 24 hours.

And Tresiba may be more effective at preventing hypoglycemia (low blood sugar) during the night in people with type 1 or type 2 diabetes. (To learn more, see the “How effective are Tresiba and Lantus?” section above.)

Talk with your doctor about whether Tresiba or Lantus are treatment options for you. Ask about any concerns, such as:

  • I take a water pill to lower my potassium levels. Is it safe to use Tresiba or Lantus with this medication?
  • How do I prevent having low blood sugar during the night?
  • I currently only take metformin tablets for my type 2 diabetes. How do I give myself Tresiba or Lantus injections?
  • Is there a special time of day that I should inject Tresiba or Lantus?

For tips on managing your condition and other helpful information, subscribe to Healthline’s online newsletter for type 1 or type 2 diabetes.

Q:

I recently started eating healthier and exercising. With my new routine, is there anything I should be aware of when using long-acting insulin products such as Tresiba or Lantus?

Anonymous patient

A:

A: Yes. If you plan to change your diet and activity level, let your doctor know so they can adjust your insulin dose if needed. This can help prevent hypoglycemia (low blood sugar).

Hypoglycemia is the most common side effect of insulin products such as Tresiba and Lantus. During your treatment, changes in your diet or level of physical activity can raise your risk for this side effect.

Talk with your doctor about whether you need your insulin dose adjusted based on your lifestyle changes. And remember, you shouldn’t make changes to your current treatment unless your doctor recommends it.

Melissa Badowski, PharmD, MPH, FCCPAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.