I just read this article and realized my puzzlement. I have given myself multiple daily injections with needle and pen for 48 years. But I don’t know what “priming” is and why it’s important. ( couldn’t be too important since I’ve had pretty good control for so long!).
So, what is priming and why is it considered so vital? I guess you’re never too old to learn!
Priming, from what I understand, is shooting out a bit of insulin (recommendation is 2u’s) from your pen before injecting, to ensure everything’s working properly. From my own personal experience, I prime the smallest amount I can (1/2u) just to make sure my needle isn’t clogged, especially since I use the same needle all day. Yesterday, in fact, I had a needle get clogged at the end of the day, so when I primed, nothing happened. I wouldn’t have realized it until the “uh-oh” after dinner if I hadn’t primed first. That doesn’t happen very often at all, but it’s comforting to see the insulin dripping before I inject, so it’s worth the small “waste.”
Guilty. I’ve been in habit of only priming pen first time. It usually takes me 3 or 4 units to get a pen going and then I tended not to worry about it after that. I’m so bad. 
At over $125/cartridge I don’t think I’m going to start priming.
If that’s bad, I think there are a lot of bad diabetics around! Pretty sure I’m the weirdo, actually bothering to prime. 
@docslotnick, I get that. If I didn’t have the ability to prime such a small amount and have such a low TDD, I might not do it (but then, maybe I would, as I’m paranoid and somewhat of a compulsive rule-follower). As it is, even with priming, one cartridge lasts me between 1-2 months, so it’s worth it for me, as I’d be tossing that little bit by the 2 month mark anyway.
@docslotnick When I started on pens (mid-1990s), the only time you primed was when you put the cartridge in the re-usable pen to make sure that the pen plunger was secure and delivering insulin.
Around the time I switched from R to Humalog, there was a pen called the “HumaPen Ergo”, which when you went to take the pen needle off it could twist out the cartridge holder so that the pen plunger was not well seated. I started to “prime” because you never knew if you were going to get insulin or not. The cartridge holder was cheap plastic and was not threaded, it just locked together with plastic tabs using a twisting motion.
They did a recall where they replaced the part of the pen that held with another part that helped, but still was a bit of a crap shoot whether the holder would twist out.
Here is the recall notice: http://www.healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2001/13990a-eng.php
Ever since that incident I am occasionally paranoid and prime to see if I have insulin coming out of a pen but I do not often do it.
I also had some problems where the pen needles were not penetrating the rubber stopper on the cartridge and no insulin would come out. I think this was on the humapen before the Luxura and Luxura HD and it may have been caused by either the pen design or the cartridge or my human error of not lining things up just perfectly. (I do not leave my pen needles on like you) I have not had that problem for a while but again, it makes me paranoid a bit.
So in short - when I stick the cartridge in the first time I will prime to make sure it is seated. After that, it is sort of rare and random and only if I feel that it is warranted.
Always prime the pen when adding a new cartridge or putting in a new needle. That’s how you know the pen advancement mechanism is up against the cartridge plunger and is actually pushing it, and the air between the cartridge and needle tip has had the air removed.
It is akin to loading a syringe from a vial, and injecting the air from the syringe back into the vial the first time you draw back on the syringe. Just removing air from the syringe.
But of course, the value of priming is proportional to the size of the injection!
If you are doing a 1/2 unit injection from a pen, you absolutely should prime!
If you are doing a 30 unit injection from a pen, that small amount of air is trivial.
So really, its importance depends on how much you are injecting
The only pen I’ve used is the Novopen 3, and I’ve only gone through a couple of them since 2001. Everything seems to line up very well, and I have to dial 10 units to have the plunger properly seat with the minimal insulin loss when I first put in the cartridge. The needle doesn’t come off the pen until the cartridge is finished.
The novopen 3 is an excellent design.
@Eric I think 1/2 a unit would cause my Bg to go up!
The Novopen 3 is built like a brick sh!thouse. Solid metal construction. I love them. When levemir came out I started using a Novopen 3 along side whatever crappy plastic pen Humalog was using at the time.
For some reason I have lost my Novopen 3 and I now use a Novopen 4 and a Novopen Echo which are nice, but do not have the strength of the 3.
They have to be pretty sturdily constructed to have lasted me this long. I still have a brand new one in the box somewhere.