Comparing Lantus To Toujeo

In our latest question and answer, the pharmacist compares Toujeo to Lantus and discusses conversions between the two.

Jul 27, 2018

Rose asked

I take 60 units of Humulin 3 times a day and 60 units of Lantus 2 times a day. How much Toujeo would I take to be equal both of the ones I take now?


Both Lantus and Toujeo contain the same type of insulin, known as insulin glargine. Insulin glargine is a "long-acting", or "basal" insulin that is generally dosed once daily (although Lantus can be dosed twice daily for some individuals).

The main difference between Toujeo and Lantus is that Toujeo is three times as concentrated:

  • Lantus contains insulin glargine 100 units/mL.
  • Toujeo contains insulin glargine 300 units/mL.

Although both Lantus and Toujeo contain the same type of insulin, studies show that Toujeo lasts a few hours longer than Lantus, meaning it provides longer glycemic control. This is most likely due to Toujeo being more highly concentrated, with the smaller insulin depot leading to slower absorption (and thus longer effects).

Converting From Lantus To Toujeo

In terms of converting from Lantus to Toujeo, the prescribing information provides some guidance:

Switching from Lantus Once Daily to Toujeo

  • Initiate therapy with Toujeo at the same dose as Lantus, meaning a 1:1 conversion. If you were using 40 units of Lantus per dose, you would start with 40 units of Toujeo.
  • It is important to note that due to the slower absorption of Toujeo, it is not uncommon to need a higher dose of Toujeo to get the same effects as Lantus. Per the prescribing information:
    "For patients controlled on LANTUS (insulin glargine, 100 units/mL) expect that a higher daily dose of TOUJEO will be needed to maintain the same level of glycemic control."
  • Most studies indicate that patients will likely need a 10% or higher dose of Toujeo to get similar glycemic control compared to Lantus. Nevertheless, to lessen the risk of hypoglycemia, a 1:1 conversion is recommended to start, keeping in mind that you may need a slightly higher dose of Toujeo over time. 

Switching from Lantus Twice Daily to Toujeo Once Daily

The prescribing information doesn't specifically list a conversion from twice daily Lantus to Toujeo. However, sources have reported that you can:

  • Start Toujeo at same number of total daily units or, to be conservative and reduce the risk of hypoglycemia, start 80% of the total daily dose of Lantus.
    • For example, if you took Lantus 40 units twice daily, your doctor may recommend to start with Toujeo 80 units per day OR start at Toujeo 64 units per day (80% of 80 units).

Additional Information

Additional conversions can be found in the prescribing information for Toujeo. You mentioned you were taking Humulin, but you don't mention if it is Humulin-N or Humulin-R. If you were taking Humulin-N, the conversion is to start Toujeo at 80% of the total daily dosage. However, since you may be taking a different form of insulin, and the fact that you were taking two different longer acting insulin products, you should discuss your starting dose of Toujeo with your doctor for appropriate guidance.

One other important point about Toujeo is that the prescribing information states that it may take 5 or more days of consistent dosing to see the maximum effect of your Toujeo dose. Therefore, it is not recommended to increase your dose more often than every 3 to 5 days.

Lastly, it is important to note that are two Toujeo products on the market:

  • Toujeo Solostar
  • Toujeo Max Solostar 

Both products contain the same insulin (insulin glargine) but Toujeo Max SoloStar can deliver higher doses per injection for those that need it.

Toujeo Max Solostar delivers up to 160 units per dose and has 900 units/pen. Toujeo SoloStar delivers up to 80 units per dose and only has 450 units/pen.


  • Both Lantus and Toujeo contain insulin glargine.
  • Toujeo is more concentrated than Lantus and absorbs slower.
  • Toujeo has a longer duration of action than Lantus and is only dosed once daily while Lantus can be dosed once to twice daily.
  • Toujeo starting doses can be determined based on your total daily dose of Lantus and other insulin you may be taking. Be sure to discuss the appropriate starting dose with your doctor.

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