I know I am super old-school (I use syringes! Only recently switched from Lantus to Tresiba!), but for those of you who use pens, does this mean you’re not able to mix insulins? I do like the convenience of throwing in a unit or two of Humalog into my nightly Tresiba injection if I need it (please don’t say “don’t mix” – it works for me!!). I have actually never even seen a pen in person; am guessing you probably can’t mix?
@JessicaD My Novolog pens don’t provide a method for mixing that I’m aware of. There may be a way to mix the 1/2 unit Novo Echo cartridges by first withdrawing some Novolog and then injecting into the cartridge, but that would be one dicey technique!
Do you actually mix the two types (Tresiba and Humalog) or do you inject separately? No judgement here, if it works for you, it works for you. Does your Endo know or endorse your method (not judgement, just interest!)?
@TomH I do mix the two – draw the longer acting (Tresiba) first, then Humalog-- all in one syringe. This methodology was sanctioned years ago when I was using regular and NPH, but I’ve never brought it up again to an endo. From experience it seems to work – Humalog seems to play well with the Tresiba and I don’t always use it and can see that Tresiba seems to work the same, with or without Humalog. I would guess that an endo might recommend injecting separately. I try to create as few subQ disturbances as possible!
@JessicaD,
I used to mix NPH and regular insulin too. That was the standard back in the old days!
But the rules on mixing have become overly cautious since then. So of course, if you ask anyone, they will tell you no!
The way Tresiba works, there is a little deposit of insulin that forms a chain after injection. And the little molecules in the chain break off slowly, from each end of the chain. Tresiba is more complicated than any of the other basal insulins!
Is it possible that adding rapid insulin into that deposit would actually affect it? I am certainly not qualified to answer that question! You would need a biochemist or pharmacologist to give a real answer.
And most doctors and endocrinologists are also unqualified to give a real answer. They just spout the same old thing - “No, don’t do it!” Without any valid research to back it up.
So the simple and unqualified answer is - if it works for you and is consistent, keep doing it!
And most important - Don’t ask anyone! Because you know what they will tell you! 
I started with single injection Lente before breakfast (age 5).
This was prescribed in 1965.
And when I started college, started seeing endo who prescribed NPH plus Reg.
I tried a pen once !! May still be in my kitchen somewhere.
Now happy with my many years with pumps. Medtronics first, and now Tandem.