Toujeo and Lantus are long-acting insulin used to manage diabetes. They are brand names for the generic insulin glargine.

Lantus has been one of the most commonly used long-acting insulins since it became available in the year 2000. Toujeo is relatively new, and only entered the market in 2015.

Read on to learn how these two insulins compare in terms of cost, effectiveness at lowering blood glucose, and side effects.

Toujeo and Lantus are both long-acting insulins that are used to treat people who have insulin-dependent diabetes. Unlike rapid-acting insulin that you take before or after a meal or snack, long-acting insulin takes more time to enter the bloodstream. It works to control your blood glucose levels for 23 hours or longer.

Both Toujeo and Lantus are manufactured by Sanofi, but there are some distinguishing factors between the two. The biggest difference is that Toujeo is highly concentrated, making injection volume much smaller than Lantus.

In terms of side effects, one important factor to consider is that Toujeo may offer less risk for hypoglycemia, or low blood glucose, than Lantus, because it helps keep blood sugar levels more consistent.

While cost and other factors might play into your decision, here is a comparison snapshot of the two insulins:

ToujeoLantus
Approved forpeople with type 1 and type 2 diabetes age 18 years and olderpeople with type 1 and type 2 diabetes age 6 and older
Available formsdisposable pendisposable pen and vial
Dosages300 units per milliliter100 units per milliliter
Shelf-life42 days at room temperature after opening28 days at room temperature after opening
Side effectsless risk for hypoglycemialess risk for upper respiratory infection

While Lantus contains 100 units per milliliter, Toujeo is three times more concentrated, yielding 300 units per milliliter (U100 versus U300, respectively) of fluid. However, this doesn’t mean you should take a lower dosage of Toujeo than you would take of Lantus.

Dosages may change for other reasons, such as fluctuations in weight or diet, but Toujeo and Lantus dosages should be the same or very close. In fact, studies show that people typically end up needing about 10 to 15 percent more Toujeo than Lantus to maintain the same fasting glucose readings.

Your doctor will inform you what dosage is right for you. The Toujeo will only appear to be a lesser volume within the pen because it is immersed in a smaller amount of carrier liquid. It’s like getting the same amount of caffeine in a tiny shot of espresso or a large latte.

If you need a high dose of insulin, you may need fewer injections with Toujeo than you would need with Lantus, simply because the Toujeo pen can hold more.

The active ingredient in both Lantus and Toujeo is insulin glargine, the first insulin that was invented to work over an extended period of time in the body. Both are delivered through disposable insulin pens, which eliminate the need to measure dosages and fill syringes. You simply dial up the pen to your dose, press the pen against your body, and activate delivery with a single click.

The Toujeo and Lantus pens are both called SoloStar and are designed to make dosage calculations simple. The manufacturer says that injection force and duration are both lower with Toujeo than they are with Lantus.

Lantus is also available in vials for use with syringes. Toujeo is not.

Both can be refrigerated if unopened. Lantus can also be stored at room temperature. Once opened, Lantus can last 28 days at room temperature, while Toujeo can make it 42 days.

Both Toujeo and Lantus effectively lower hemoglobin A1C numbers, which represent an average blood glucose level over time. While those averages may be the same on either formula, Sanofi claims that Toujeo provides more consistent blood sugar levels throughout the day, which may result in fewer ups and downs in energy, mood, alertness, and hunger levels.

Lantus begins to work one to three hours after injection. It takes 12 hours for half of the dose to be eliminated from the body, which is called its half-life. It reaches a steady state after two to four days of use. Steady state means the amount of medication coming into the body is equal to the amount going out.

Toujeo appears to last slightly longer in the body, but it also enters the body more slowly. It takes six hours to start working and five days of use to reach a steady state. Its half-life is 19 hours.

Research shows that Toujeo may offer more consistent blood sugar levels than Lantus, which may reduce the chance of low blood sugar. In fact, according to one study, those who use Toujeo are 60 percent less likely to have severe hypoglycemic incidents than people taking Lantus. On the flip side, if you take Lantus, you might be less likely to get an upper respiratory infection than you would as a Toujeo user.

Still, low blood sugar is the most likely side effect of taking Toujeo, Lantus, or any insulin formula. In extreme cases, low blood sugar can be life-threatening.

Other side effects may include:

Injection site reactions might consist of:

  • loss of fat volume or an indent in the skin
  • redness, swelling, itching, or burning where you used the pen

These effects will usually be mild and shouldn’t last long. If they persist or are unusually painful, speak with your doctor or pharmacist.

A search of several pharmacies online shows Lantus priced at $421 for five pens, which is slightly more than the equivalent three pens of Toujeo at $389.

It’s important to check with your insurance company to find out how much they will be paying and how much they require you to pay. After insurance coverage, it’s possible that Toujeo could cost you the same amount or less than Lantus.

Be on the lookout for less expensive, generic forms of insulin, called biosimilars. Lantus’s patent expired in 2015. There is a “follow-on” drug, which is created like a biosimilar, on the market now called Basaglar.

Remember to check with your insurer, too, as they might insist that you use a less expensive version of whatever insulin you choose to use. These are factors you can discuss with your pharmacist, who will often know the ins and outs of your prescription insurance coverage.

Toujeo and Lantus are two long-acting insulins that are very similar in terms of cost, effectiveness, delivery, and side effects. If you are currently taking Lantus, and you’re happy with the results, there may be no reason to switch.

Toujeo may offer some advantages if you experience blood sugar fluctuations or have frequent hypoglycemic episodes. You might also consider switching if you are bothered by injecting the volume of liquid that Lantus requires. On the other hand, if you prefer syringes, you may decide to stay on Lantus.

Your doctor can help you navigate decisions about which insulin to take, but always check with your insurance company to make sure it makes sense cost-wise.