Basal insulin - "strength" or "duration"

I recently started using Levemir. (See thread: Lantus and Levemir comparison)

I ultimately ended up using both Levemir and Lantus (not mixed, but at different times), but when I first started with Levemir, I was using only it, and I did 2 injections, morning and night.

When first starting, it took me some time to get the right dosage. The same dosage of Levemir and Lantus didn’t work. Levemir seemed “stronger” than Lantus, and I had to reduce the amount I took.

I also noticed that Levemir did not last as long as Lantus.

So I had a bit of a light-bulb moment on it. Perhaps I was wrong in thinking that it was not as strong. Maybe the strength of Lantus and Levemir were the exact same, but what I was seeing was a difference in how long it lasted…

So when I looked at the numbers, they made sense, they matched up perfectly.

Let me give an example:

  • For me, Levemir lasts 12 hours, and Lantus lasts 16 hours.
  • And what now seems to not be a coincidence, 6 units of Levemir seemed to have the same effect as 8 units of Lantus.

So perhaps “strength” is the wrong idea. Look at how these numbers work out.

Because figuring out the exact duration for basal insulins is one of the most challenging things people have to do, this is possibly a very useful thing to consider. If you know one, it can help you calculate either a dosage conversion or a duration difference.

As a side note:
Going further, as just conjecture and something to toss around, is all insulin - basal or rapid - the same “strength”, it just comes down to how quickly it works?

Someone says they need more NovoLog than they do Apidra. Maybe it’s just slower not weaker.

I am not staying this is true, but I wanted to put this thought out as a mental exercise. What can you come up with?


By convention, at least by design, a unit of levemir should be equivalent to a unit of Lantus in terms of how many an individual would have to take to accomplish the same goal over a long enough period of time to cancel out their differences in duration. It seems that you just respond more efficiently to Lantus, or maybe there were other unknown variables or mechanisms at play, but the entire concept of the standardized “unit” is that in theory they’re supposed to be equivalent without duration entering the equation whatsoever---- just as in theory someone would have to pump the exact same number of rapid insulin units as they would have to inject with long acting basal although we all know it doesn’t necessarily work out that way in reality, most people actually end up pumping less when rapid basal is used because their body absorbs it more efficiently-- but that is the basis of the conventional standardized “unit” is that a unit always = a unit, duration irrelevant.

I think it’s just mere coincidence that you require more levemir in an amount that seems to correspond with the duration

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It could be the opposite, depending on what is meant by “efficient”. Less Levemir was required to hold me steady. I also know Levemir did not last as long.

I am not sure you could say one is more efficient than the other. Requiring less but not lasting as long - is that more efficient or less efficient for a basal that is supposed to “in theory” last all day?

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I must have misread I thought you were noting that u needed less Lantus… our bodies all absorb different insulins somewhat differently, but by design a unit = a unit…

A unit of novolog lasts approximately 4 hours whereas a unit of tresiba lasts approximately 40… one would expect to need approximately the same amount per day if used as basal though… one would certainly not expect to need 10x of either one vs the other

I think you are missing the point of what I was trying to say. I needed less Levemir. But…

I guess so… all these numbers just make me glad I switched to a next generation basal and have never had to think about it again:)