Tresiba: how do I calculate my daily dose?

I take X units of basal insulin daily. Tresiba lasts longer than 1 day. Should I take less each day or take it every other day?

NO! You should do neither! Tresiba is a once-daily basal insulin that can be taken at any time of day, but must be taken every single day. For users already on insulin therapy and switching to Tresiba, they should start with the same number of units of Tresiba as their previous total daily basal dose.

Many users, myself included, were concerned about the potential stack effect and ultimately over-dosing of an insulin like Tresiba that lasts longer than 1 day, if taken every day. Fortunately though, this is not an accurate understanding of how a long duration insulin, taken daily, actually works.

In an ultra-long acting insulin like Tresiba, the dose dissipates over the entire approximately 42-hour duration. Conceptually, during the first 24 hour day, only 24/42nds of the dose have been metabolized. And on the 2nd day, the remaining 18/42nds of the dose, plus a new 24/42nds from that day’s new injection will add up to equal the full metabolic dose. Essentially, after a few days to allow the dose to stabilize, the user is injecting X number of units every single day, and X number of units are wearing off each day— they’re just not all entirely the units from the previous day.

The following image can be helpful to understand how the daily layering of an ultra-long acting basal like Tresiba results in a steady coverage with minimal peaks and troughs

This is a very easy topic to overthink. The good news is that the reality is the most simple one possible-- that Tresiba is dosed 1x daily with the patient’s full basal dose each day and its ultra-long action results in a very smooth basal coverage.


  1. Tresiba package insert
  2. Haahr, H., & Heise, T. (2014). A Review of the Pharmacological Properties of Insulin Degludec and Their Clinical Relevance. Clinical Pharmacokinetics, 53(9), 787–800.

End of wiki ---------- comments start here


Possibly mention that adjustments should be made only after using for several days? Or maybe that should be a separate post?

I was envisioning a separate post for that but suppose I could combine

Actually, separate is better! More content.

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I wouldn’t assume fair use – especially without attribution. Did you try TinEye?

No, I don’t know what that is and it’s the sort of nonsense I’m concerned about with real “content” vs the bs sessions where I really shine

It’s from Novo Nordisk. Fair use given the number of images in the paper. >>

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Can you add an appropriate reference for the pic?

Harvard style:

Haahr, H., & Heise, T. (2014). A Review of the Pharmacological Properties of Insulin Degludec and Their Clinical Relevance. Clinical Pharmacokinetics, 53(9), 787–800.


Bumping this, didn’t realize it has been saved in content team category instead of published

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Is it ready to push out to a wiki? I could just move the thread, and put a bit of wiki formatting at the very end. I am now thinking that keeping the pre-publishing comments is actually helpful.


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I’ll do it in a couple of hours as soon as I am back home.

I should be getting Tresiba in the mail in the next day or two. I’m currently using 23 units of Lantus everyday (split into two doses). My doctor told me that people generally need to take more Tresiba than Lantus and recommended that I start on 33 units/day. She said she thought I’d end up with between 30-33 units/day. Not sure why we’re starting at the upper end of that interval… I’d probably prefer to start at 30.

This post seems to contradict the idea that I would need to take more Tresiba than Lantus. Are you recommending maintaining the same dose in a switch to ensure that lows don’t occur? Not because of the stacking explained in your post, but because that’s often the method used when starting a new basal insulin (start low, increase incrementally… as I said, I have no idea why my endo recommended starting high).

I’m worried I’m starting too high, and I’m going to have severe lows.

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I dunno what your doc is thinking… maybe he has a track record with tons of patients switching to the point he thinks that’s a good recommendation—— but it seems like a weird assumption to me…

The package insert says to switch 1:1… that said I don’t think the insert necessarily outweighs decades of practicing medicIne with thousands of patients…

I did myself actually end up taking a few extra units of tresiba vs Lantus… but this became clear over weeks, I definitely never wished I’d made such an aggressive move preemptively


That’s good to know. It’s a little comforting that you ended up needing to increase your dose. I’m thinking I might start around 25 instead. I’ve heard you don’t want to change the dose until several days in (probably 5?). Looks like you might’ve written another wiki about it so I’ll check that out.

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I think they say 3 days as a minimum… but if you say 3, people cheat it down to 1 or 2…

If you say 5 people cheat it down to 3


Just be careful, I find I need much less of it than my total daily dose of Levemir, at least for now (2-3 weeks in). I was taking 18-20 units of Levemir depending on the day, and I am currently taking 13 units of Tresiba daily (and still find it a bit too strong).

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Did you ever take Lantus?

Nope, though I would think it’s similar to Levemir (except for the duration) but could be wrong. I was a long time pumper (and may become one again since I don’t Tresiba is that amazing honestly), so this MDI stuff is all new to me!