Switching from Lantus to Tresiba

As indicated in a few other threads, I’m switching from Lantus to Tresiba today. I’ve had some trouble determining what my starting dose should be, so I thought I’d create a thread documenting how a 1:1 conversion worked for me (really, this was @Michel’s suggestion).

I generally take a total of 23 units of Lantus everyday, so I’ll be starting with 23 units of Tresiba per day. I did my last Lantus dose of 10 units at 5 PM yesterday (a little late for me). I did my first dose of Tresiba at 7:30 AM this morning. I’ll have some leftover Lantus on board from yesterday evening’s dose for a portion of today, but that may be helpful since it takes a few days for Tresiba to take full effect.

I’m planning to wait to make any dosage changes until after the 3rd day of Tresiba because I want to make sure I’m making dosage changes based off of Tresiba at it’s full effect. I’ll post an update either later tonight or tomorrow morning. Depends on whether things get interesting :wink:


Good luck with your switchover! I really hope Triseba works as well for you as it does for some users here at FUD!

For what it’s worth, EH’s (now former) endo prescribed a 1:1 Triseba to replace Tuojeo amount and it was way too much. He was drifting really low all night and it was somewhat concerning. Worked out fine in the end, he dialed it back 20% and that didn’t make him crash as badly.

I think others have had the exact opposite experience - 1:1 worked fine. So, we will look forward to having another person’s experience to learn from!


This is a good plan unless you’re running low once your Lantus has worn off—if you are, I’d adjust ASAP, since it’s only going to get worse as it all kicks in. It seems to me to be true, anecdotally, that most people end up needing less Tresiba than Lantus (was the case for me), but there are definitely people who go any which way. Good luck!


Sounds like you were dosing Lantus twice a day in different doses, but in order to understand better, what was your previous dosage schedule times and amounts with Lantus? And what’s your average TDD including bolus insulin, eating schedule, diet type, etc.?


Yeah, I suppose I’ll have to adjust early if I drop low. It’s unlikely I’d drop low the first day or two though because I won’t be at the full dose until I’ve been on it for close to a couple days. Who knows though, it’s definitely something to watch for.

@jag1, my Lantus doses were at 7:30 AM (13 units) and 4 PM (10 units). I dosed more in the morning because I had a tendency to fall low at night around 4 AM (especially when I’m swimming laps regularly). I recently started swimming again :slight_smile:, but I took a break for a couple months so I need to build up my fitness level again. I do not consider myself an athlete. I like to swim for 30 minutes 3 times a week. Generally freestyle most of the time, but I definitely get my heart rate up and am out of breath throughout most of the swim.

I give myself 1 unit of humalog for every 8-10 carbs I eat, depending on time of day. My eating schedule varies. I don’t adhere to a strict diet of any sort, and I have no interest in doing so :slight_smile: Most of the time, I opt for low carb meals during the day… mostly gourmet salads for lunch, sometimes vanilla yogurt for breakfast or a piece of fruit… often nothing but coffee for breakfast. I have to give a unit of Humalog around 8-9 AM most mornings whether I eat or not. Dinner is whatever I want, but probably somewhere between 30-60 carbs. Sometimes more. I usually have some wine a couple nights a week. I often have a snack in the evening after dinner, and I generally just eat whenever I’m hungry- though I don’t tend to eat that many snacks. Sorry I can’t give you a better TDD estimate, but I’ve never really bothered tracking that stuff. It just didn’t seem to be that important to me.

I’d be happy to answer any other questions you have.

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This is the problem with stacking 2 different basals. If you’re running low today is it because of lasts nights Lantus on top of this mornings tresiba? It’d be impossible to know… then if you dial your tresiba dose down in response and it wasn’t actually necessary, then if you’ve set the frustration roller coaster in motion and end up chasing your dose around it might not be as good an experience as otherwise

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My Lantus has worn off completely by now. I was running a little low this morning, but I seem to be running on the high end now. I won’t make any changes based on my blood sugar levels during the day today. However, if I drop low tonight, then I will likely decrease my Tresiba dose tomorrow morning. If I run high, I probably won’t change anything.

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Well Lantus is advertised to last 24 hours… many people find that it doesnt, but it’d be really hard to tell what’s what within 24 hours of a Lantus dose id think


Yeah, but I did the dose at 5 pm last night, so it certainly shouldn’t affect my blood sugar levels overnight.

Thanks for your reply. If you’re eating only 100g carb a day, then that would only be about 10 units of Humalog. That would mean your fast-acting insulin is only 30% of your TDD. Does that sound about right, or do you think you’re averaging more than 10 units of Humalog per day?

I don’t really track my TDD either, but I do record my injections in my meter, and that allows me to go back and see what my average TDD and basal/bolus ratio have been, and I find that useful.

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Yeah, that’s probably an average day. Some days I’m sure I eat more though.

70% basal ratio is fairly high compared to most other T1’s, but everyone is different and if it works, it works, so I’m certainly not suggesting that you should change it. It does make me wonder, though, whether you might be covering some of your food requirements with basal insulin, especially since you take a larger injection of Lantus in the daytime than at night. That could mean that you may end up with a smaller Tresiba requirement (maybe 20 units?) but you will be able to find that out as you track it. Good luck; this will be another interesting test case.


I tend to think this is a very common occurrence … you explained it well

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But this is because most other T1s eat 200-300 grams of carbs, no? My understanding is that everyone eating a low-carb diet will, by nature of the fact that they’re eating low-carb and not bolusing much, be taking a larger proportion of basal insulin than the majority who eat high-carb diets. If the OP were eating 250 grams of carbs per day (pretty typical for a non-low-carb diet) then they’d be taking 25 units of Humalog, which would equal about a 50/50 split.


I timed my Lantus doses so that the small peaks lined up well with when I would eat, but I think if I were using basal to cover my food requirements, then I would drop low when I wasn’t eating. This generally wasn’t an issue for me during the day, but I did tend to eat at the same time everyday so it’s difficult to tell. I didn’t realize that 100 grams of carbs was that low. I can’t even imagine eating 250 grams everyday. I probably have on occasion, but that just seems like a lot of food to eat everyday!

Anyway, no lows during the night, so I gave the full 23 units again today. I did have a small drop around 4 AM, but overall I was pretty flat during the night. Actually, a little better than I’ve seen with Lantus. This makes me wonder if my dose may be a little too high because I only have 1 day’s worth of Tresiba in my system. Perhaps once I have three day’s worth, I’ll be dropping low during the night. We’ll see.

I did notice that I was a little more sensitive to carbohydrates yesterday, and I needed to take more insulin to cover them. My post meal spikes were a little higher than usual, and it seemed to take more insulin to bring them down (not too high… around 200-210, but it still took awhile for them to come down). Once they came down, I had trouble with lows sticking around despite corrections. I’ll try to pre-bolus a bit better today.

I often have a little trouble with a spike in the morning so I usually need to give myself 1-2 units of humalog. No spike today :slight_smile: I even had a morning coffee and experienced no spike whatsoever. In fact, the last 6 hours are a beautiful flat line.


Great news!

Really great. I can’t wait to see how tonight will go. Keeping our fingers crossed for you here fopr no lows!

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Yesterday was a little confusing. After posting about that beautiful flat line, I had to snack for a few hours without bolusing to avoid going low. I then figured that I’d be struggling with lows all day. However, that seemed to fade in the evening, and I struggled with highs during the night. I’m hesitant to attribute this to Tresiba because it’s inconsistent with what I experienced earlier in the day and the previous night. I’ve decided to attribute it to my dinner containing a decent amount of fat (but not so much I’d expect to still be digesting 10 hours later…). I’m still going to take the same dose of Tresiba today.

I’ll make an effort to eat a little lower carb and less fat this evening. This evening is especially important because I should have 3 days worth of the same Tresiba dose on board at that time, and I can solidly base any dosages changes off of how things go. Not saying I will make changes, but at least it’d be representative of the full Tresiba dose if I did make changes.


I had to give a little fast acting before going to bed last night. Around 2 AM (blood sugar at 100), that had worn off, and my blood sugar rose to a little over 180 by 6 AM. Looks like what happened the night before was a legit sign that I needed more basal.

I’m upping my dose today to 24 units. We’ll see how this plays out during the day. I do feel like I’m a bit less sensitive to my fast actin insulin during the day, and there’s a possibility that could be because my long-acting isn’t quite up to par. But I’ve had such beautiful flat lines in the morning, and I’d like that to continue. I guess we’ll see how the new dose goes!

No huge problems so far with Tresiba though. I’m enjoying only taking one long-acting insulin injection a day, and I’ve had decent blood sugar levels overall, even though there has been a problem with highs at night.

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It would make sense, since Tresiba requires 3 days to establish. @Sam had a cool wiki about this:

I particularly liked the triple Tresiba curve, which makes a good visual case.

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Yes, that is a wonderful illustration. Makes sense that the highs were a bit more of a problem the second night than the third. I’m glad I waited to make any adjustments until 3 days had passed.