Is Lantus Long Acting? Plus, 9 Other Lantus FAQs Answered

Lantus (insulin glargine), a popular long-acting insulin, has been around for over 20 years. But questions still arise about how long it takes to work, whether it has a generic version, and more. Even if you know the answer, you may be curious why — even if you’ve been using Lantus for years.

Below, we answer 10 common questions about Lantus to help you better understand your medication. 

1. Is Lantus long acting?

Yes, Lantus is considered a long-acting insulin. Its effects last for 24 hours, which is why you usually need to inject it only once a day. Lantus helps manage your blood glucose (blood sugar) levels throughout the day, even when you’re not eating. So it’s sometimes called background or basal insulin.

Most long-acting insulins work for 24 hours. But some work longer, including Tresiba (insulin degludec), which lasts up to 42 hours.

2. How long does it take Lantus to work?

After you inject Lantus, it’s slowly released and absorbed by the body. So it doesn’t take effect right away. It usually takes 1.5 to 2 hours for Lantus to start working. Toujeo, a concentrated version of insulin glargine, takes longer — about 6 hours.

3. Does Lantus have a peak time?

No, Lantus does not have a peak time. Instead, it delivers a slow and steady amount of insulin throughout the day. This is different from shorter-acting insulins, which cause insulin levels to climb more quickly, peak, then fall back down.

4. What’s the maximum dose of Lantus?

There’s no specified maximum dose of Lantus. But there are limits to how much you can inject at a time.

For example, each Lantus SoloStar pen contains 300 total units of insulin. You can inject up to 80 units at a time. A Lantus vial contains 1,000 total units of insulin. Using a U-100 syringe, you can measure up to 100 units (1 mL of liquid) per injection. But for higher insulin doses, injecting a larger volume of liquid can be painful. What’s more, you may not absorb the insulin the same way as you do with lower volumes.

In this case, Toujeo or Toujeo Max may be an option to consider. These products contain a greater amount of insulin glargine in a smaller amount of liquid, making larger doses more manageable. The Toujeo pen can provide 80 units per dose but with less liquid than Lantus. The Toujeo Max pen can provide up to 160 units of insulin at a time.

5. Does Lantus have a generic?

No, Lantus doesn’t have a generic. Lantus is a biologic — a medication made using a living system. Instead of generics, biologics have biosimilars, which are highly similar (but not identical) to the original (reference) biologic.

Lantus has two biosimilars (Semglee and Rezvoglar) and an unbranded version. There are also a few other insulin glargine products, including Basaglar, Toujeo, and Toujeo Max.

6. Can Lantus and Humalog be mixed?

No, it’s not recommended to mix Lantus with another insulin in the same syringe, including Humalog (insulin lispro). That’s because the other insulin may interfere with the acidity of Lantus, which plays an important role in how it’s released in the body. Lantus and other insulins should be injected separately.

7. Do any medications interact with Lantus?

Yes, insulins such as Lantus can interact with other medications. Examples of these include:

• Other diabetes medications, such as sulfonylureas, which can increase the risk of low blood sugar

• Beta blockers, which can weaken Lantus’ effects and mask certain symptoms of low blood sugar

• Certain antibiotics, which can increase the risk of low blood sugar

• Medications that can raise blood sugar levels, such as corticosteroids

Your healthcare team can review your medication list for potential Lantus interactions. In many cases, you can manage these interactions with blood sugar monitoring and dosage adjustments.

8. Is Ozempic or Lantus better?

Ozempic (semaglutide) and Lantus are two injectable diabetes medications, though Ozempic also comes in pill form. Neither medication is better than the other. In fact, there are specific reasons why you might be prescribed Ozempic, Lantus, or both.

If you have Type 2 diabetes, for example, a long-acting insulin like Lantus is usually recommended if your blood glucose level or hemoglobin A1C (HbA1c or A1C; average blood glucose over 3 months) is very high. Long-acting insulins are also usually part of Type 1 diabetes treatment.

Unlike Lantus, Ozempic is approved only for Type 2 diabetes and isn’t a type of insulin. But it does cause your pancreas to release insulin after you eat and lessens the amount of sugar your liver makes. It can also affect your appetite and fullness, resulting in weight loss. What’s more, Ozempic has proven cardiovascular and kidney benefits for certain people with Type 2 diabetes.

If you’re living with Type 2 diabetes, Ozempic’s effects can work with Lantus and provide additional benefits. In fact, experts recommend adding a medication like Ozempic to insulin therapy. But there are certain situations in which Ozempic may not be appropriate. Examples include having a history of certain types of thyroid cancer, pancreatitis, or allergic reactions.

8. Does Lantus affect the kidneys?

Lantus isn’t known to harm the kidneys. But certain side effects, such as hypoglycemia (low blood sugar), may be more likely if you have kidney problems.

As part of your diabetes treatment plan, Lantus can have positive effects on kidney health. That’s because high blood sugar levels can damage the blood vessels in the kidneys over time, leading to chronic kidney disease. Keeping your blood sugar levels within your target range can help lower the risk of this long-term complication.

10. How long can Lantus be out of the fridge?

Unused Lantus SoloStar pens and vials last until their expiration date when stored in the refrigerator (36℉ to 46℉). But they’ll last for up to 28 days if they’re kept out of the fridge at room temperature (up to 86℉).

After first use, you should keep Lantus pens out of the refrigerator. In-use vials can be stored in the refrigerator or at room temperature. Throw away any unused insulin after 28 days (or by the labeled expiration date, whichever is sooner).

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Written by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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