Switching from Lantus to Tresiba; advice?

I’m switching from 16u of Lantus at night to Tresiba, but my doc didn’t really give me much to go on or clear instructions. The script says the same amount of units but I think I might dial down a couple just until I adjust.

I’m nervous since I’ve been on Lantus since diagnosis 6 years ago, but have read mainly good things about Tresiba! Anyone have any advice before I switch? I’m hoping to have a smooth ride with no adverse reactions or anything. If you have any previous threads on here to share feel free! I’ve been reading as much as I can on it before the switch.

I still have a box of Lantus pens but want to switch before I use them up just in case things don’t go as planned. Any tips or advice would be appreciated! Thanks all!

When I switched to Tresiba, I just switched (it was from Levemir, but I’d been on Lantus before that). Same units, it was no problem. Lantus had a much more variable activity for me (that’s by design I think), so you may have some initial unexpected trends with the change. Test a lot during the first days and weeks until you know how it’s working for you.
Good luck!

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When I switched from Lantus to Tresiba it took about 2 weeks for me to adjust the Tresiba dose. My switch was made because I had basically given up on Lantus, I was constantly tinkering with my dose with limited success.

I found that each change in Tresiba dose takes about 3-4 days to settle in. I started lower than my Lantus dose and looked at my basal trend on the CGM and adjusted the dose upward every 3-4 days. I also found that the Tresiba dose (for me) has to be spot on. Even varying the daily dose by 1 unit seemed to make a big difference; Lantus seemed a little looser to me on the dosage.

After being on Tresiba a while I’ve noticed the dose seems to be more dependent on maintaining a consistent daily activity level than Lantus. I guess that makes sense with the long action time of Tresiba. I’m usually active, and when I’m not active I’m on my feet a lot. If I get out of that routine, such as a lot of sitting around over the holidays, the only way I’ve found to stay in decent BG range is frequent correction bolusses. I have not had good results with increasing the Tresiba dose to accommodate inactive days.


I switched over to Tresiba from a combo of Lantus and NPH (weird I know) and the conversion ended up being pretty different, but from what I’ve heard Lantus to Tresiba is a 1:1 ratio. The Tresiba packaging does have a section in it that says 0.4u per KG of body weight so that may give you a good comparison.

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My daughter switched from Levemir and she takes 25% less Tresiba. Like others have said, it takes a solid 3 days to see the full effect of a change. I would also agree that once it’s tuned into the right dose, 2 units one way or the other have a big impact. Overall, we really like Tresiba over Levemir. The only drawback we see is the inability to increase/decrease day/night doses, so we have set her perfect daytime dose for Tresiba and her overnight needs are lower, so she goes to bed at a higher number and gradually drops overnight about 4mmol and wakes up in perfect range. We realize a pump would be ideal in this situation, but we have no interest in pumping, so we are quite happy with the switch to Tresiba (Levemir wasn’t cutting it anymore)

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I was taking Lantus 2x a day, which made the transition slightly trickier (but not bad), but if you’re only injecting once a day, I would just take the same amount or slightly less at your usual time and give it several days to see how that goes. I did reduce my dose going from Lantus to Tresiba (I think at the time I went from 20u of Lantus to 18u Tresiba, which I’ve lowered further since to 16u), so my suggestion would be to err on the side of a slightly reduced dose (14u maybe?) to start, knowing the first few days you might need to correct more often as it kicks in and/or may need to raise the dose back after that.


When I switched from Lantus to Tresiba it was because I was having too many crashing lows with Lantus. But I try to keep my what sugars as close to normal range as I can, so I don’t keep much buffer.

I tried using the same amount as Lantus, but dropped two units after only a couple days. I still had to cut back a couple more times. Eventually I ended up using six units less that I was with Lantus.

I did see some changes in how a low develops. The feeling is slightly different and the progression is slower. Also, it doesn’t happen much. While I was working my way down with Tresiba I noticed that my Humalog seemed more effective. I had to dial back that for a while. Now that I have settled in this has all gotten back to normal for me.

I am way happier with Tresiba and how it works than I was with Lantus.

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Thank you all so much for the replies!! Sorry I have been MIA, but I got a lot of info just in the right amount of time! I finished my Lantus pen last night, and am starting Tresiba tonight! I’m going to go with 14u starting instead of 16 and see where I end up. Fingers crossed, hoping I don’t have too many lows. I’m hoping it works just as great for me as so many of you! I appreciate the help!! :slight_smile:

Hello Mila.
Yes, still reading here. Interesting stories. As I stated in my initial post, I am taking 66 units of Lantus at bedtime yet the sample box of Tresiba that my doctor gave has 10 units 1x day and to increase 1 unit up or down as req’d. Everything I’ve read so far bot here and the Tresiba site say that switching long lasting insulin can be a 1:1 ratio or reasonably close. I just don’t want to go from the 10 units to taking say, even 60 or 62 units and have a wild LOW as a result. I really do not like that, as I am sure any T1D would not. Plus, I don’t know well enough to stop eating and usually end up high having to take Humalog to compensate…argghh…what a vicious cycle. Hoping someone can chime in and share their experience with switching from a 1 time fairly large dose of Lantus at night to Tresiba and the amount they started with, how long it took to adjust to get normal BG, etc.
Thanks! Hang932

@John58 pretty much hit it spot on, and anyone switching should read his words carefully and repeatedly. (I would also add that I think he may have (appropriately) understated the drama that can accompany the transition–it isn’t easy.)

One more bit of advice: the hair-trigger qualities of tresiba is such that I wouldn’t advise anyone to do it without a CGM, or you’re going to be in for a very wild roller coaster ride for at a couple of months… and that assumes you’re on top of it every moment. (With a CGM, my wild ride took about 6 weeks, that’s because you need to experience the whole range of lifestyles–active vs. non-active and other tilts that life tends to deliver.)

In the end, my personal experience is that tresiba may have some benefits, but they’re negated by the drawbacks – in short, it’s a wash. My advice is that, if you’re even moderately good with Lantus, you’ll find that the big, arduous transition to Tresiba will land you with roughly the same level of control as you had with lantus (and the same mixed bag of headaches, though the “mix” will be shuffled around).

Obviously, not everyone is the same, so take my advice with the same grain of salt that you would with anyone else’s advice.


You’re changing from one basal insulin to another. The difference is the action profile and longevity, but if anything it might be easier to get a flatter more consistent level of control.

I’m not saying that you won’t need to make adjustments. Expect that. And, from what I understand it takes longer to make adjustments (titrating every 3 days rather than daily until dosage is dialed in), but I don’t see why weight gain should be an issue long-term

Best of Luck.

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It may be too simplistic to say they’re just two different types of basals. The actual insulin proteins are physically identical (among all insulins), but it’s the [chemistry] buffer that affects the time required to release the insulin. Buffer chemistries between basals all vary, as do the way those chemistries interact with your body chemistry.

Hence, the paradox that biochemists face in achieving a “flatter and curve” is that human biology is neither flat nor consistent, so it’s simply not possible to create a set of chemistries that reacts the same all the time.

Consider those who use a pump and happen to have the flattest and best BG control. That is, just using a pump doesn’t give you flat BG curves. To get that, you have to vary basal rates programmatically in the pump to match your biology. This may range from .5u/hr to up to 2u/hr over a 24-hr period, depending on individual metabolisms. And even those calcs change for events like holidays and vacations, work trips, school schedules, etc. These experiences make ones body more or less sensitive to insulin, but also to carbohydrate metabolism, etc. Then one must take into account physically active days vs. less active days, and so on.

In short, optimal control is not possible unless you’re willing to do a combination of self-mitigation of variations in your life (which can be easier or harder for some over others) and stricter attention to bolusing with either insulin or carbs as needed to smooth out those unexpected curves resulting from metabolic variations in your body.

Personally, I’m happy to artificially restrict my daily activities to favor “predictable routine” of activities, carb intake, and other events. But that still leaves a lot of wiggle room in metabolic reactivity to insulin.

I don’t like the pump primarily because the level of work needed to manage the device doesn’t offset the benefit received when compared to the relatively minimal work associated with a basal insulin.

So, when picking which basal insulin is right for any individual, it may certainly be that Tresiba has a flatter curve (and last longer?) than Lantus under some conditions for some people, but I’ve personally found “long and flat” is not necessarily “good” because it requires you to be static in your lifestyle all the time. If you vary anything, that long-lasting Tresiba is almost assuredly not going to perform how you need it for at least a few days.

Although basals vary among individuals, I can speak for myself (though I’ve found many others echoing the same observations) that Tresiba will peak with optimal performance between 5-10 hours after injection. Here, my bolus calcs is about 1u/20g. After 10 hrs, the insulin carb ratio increases to 1u/40, which will go to about 24-30 hours. To truly “flatten” it out for me, I had to break it up into two doses: 7am and 2:30pm – the latter was necessary because if it were later than that, my BGs would crash during the night. Any variation on that would require lots of boluses and glucose tablets to keep things stable if my activities and eating didn’t match what Tresiba was doing.

With T1D, the best control is not the result of how well you do when you’re in your routine, it’s how well you do when you’re not. Once that BG roller coaster starts, it’s a nightmare to get off of it, and can throw you off for a long time. Tresiba causes more roller coasters for me than Lantus ever did, primarily because Lantus didn’t last as long. I could start afresh each day, and not worry about what I did 1,2 or 3 days ago.

My personal experience over the past 45 years with diabetes has taught me that the “optimal” basal insulin is one that works for about 12 hours because life presents those unexpected curve balls, where your routine will be disrupted. I don’t want to be handcuffed to an insulin that will require 3-4 days to readjust when something different happens.


I personally had a bad experience with tresiba. I was taking a lot less humalog when I was taking tresiba. Tresiba specifically says to carry a sugar supply on hand with you at all times. Not every long term insulin says that. So just be aware. You should be careful at night when you’re sleeping. But that was my experience. I’m not saying it will be the same for you. I think doctors should be more clear and specific. It’s not to be vague or general saying or thinking that they are all the same.

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Have you tried Levemir? It lasts almost exactly 12 hours at smaller doses.

I haven’t tried Levemir. I actually had no desire to change from Lantus, frankly, but I met a few people who were happy with it, so I thought I’d give it a try. I should have remembered the old phrase, “if it ain’t broke, don’t fix it.”

But that doesn’t mean Lantus doesn’t have some drawback, as all insulins do. Lantus actually does have a residual decay period that can take some time, but the level of insulin during that tail is largely minimal. Now that I’ve returned to it, I’ll be a lot more aware of the pros and cons given my recent history with Tresiba fresh in mind.