Insulin: syringes vs pens

Of all the options for small doses, the syringe is the worst… standard novolog flex pen is better-- other options out there too like the novopen echo and junior allow for half unit dosing but I don’t think they can accurately dose 0.5u— but personally I think the best bet is to keep it simple with the throwaways

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Yeah, I’ve come to realize syringes are not my best bet, but I’d already been using syringes with the pen I’m on, so have to stick with it til I get more (at least from what I was told). I’m no longer dosing JUST .5u anymore (I’ve relaxed more on my carb intake, for one thing…), so that wouldn’t be an issue, but I do want the ability to dose 1.5/2.5, etc, so I’ll see if she’ll prescribe one of those - thanks.

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The NovoPen Echo can dose 1.5, 2.5 units and so on. I’ve heard of other brands of half-unit pens that they don’t accurately dose anything below 1.0 units, even though there is a 0.5 marking. I haven’t heard either way whether that’s true of the NovoPen Echo. It has a 0.5 unit marking, so it may be possible. The NovoPens in general are so much higher quality than anything else that it wouldn’t surprise me.

I’m no help with the Afrezza, but good luck with that! Insurance companies should cover more than one type of insulin, since people need different types for different circumstances.

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At the risk of sounding like the grouchy old man yelling “get off my lawn”, I’ll say that I still use syringes and bottles and I’m very happy with them (42 years on).

I can accurately measure to 1/2 unit (since my syringe is marked in 1/2 units), and in fact can measure even more precisely than that since I can stop the syringe anywhere between the two unit marks that are 1/16" apart (not as hard as it sounds if you have good eyesight). Since a pen is either full or half unit only, I would argue that a syringe is therefore actually superior to a pen in this regard.

Also, a bottle and a syringe are compact compared to a pen, and more easily fit in my pocket insulin/meter case, and a bottle holds much more insulin and lasts much longer than a pen so I don’t need to worry about carrying an extra. Of course it also generates less medical waste, which I feel good about.

Finally, when I’ve tried pens I have found them bulky to hold and therefore relatively uncomfortable to inject with (like writing with a large magic marker instead of a pencil). Plus I found there was always some leakage when I removed the pen needle from my skin, no matter how long I waited; in contrast that never happens with my syringe.

None of this would prevent me from using a pen if that was the only way I could buy an insulin that I wanted to use, though I don’t see why any manufacturer ships an insulin in pens only except to increase their profits (with the exception of non-U100 concentrations of insulins). So unless and until there is something significantly faster than Humalog that is available only in pens, I see no reason to change.


That’s the thing… there’s just enough slop in the mechanism that an amount less than 1u (which is a tiny tiny amount of liquid) can’t be delivered accurately… that’s why pumps can deliver smaller doses… because they’re essentially continuously pumping and therefor there’s no slack in the system like you’d get with the start/ stop of a pen… (interestingly, that’s also how trains start moving) and of course pumps have more precise control mechanisms too…

But to the original question, I do believe the concern of insurance denying afrezza because they approved novolog is a non issue. They’ll approve what they approve automatically and make you fight for anything else but I don’t believe one will affect the other in my experience…

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I just looked up the Echo user guide, and it says that it can deliver 0.5 of a unit: “The pen injector allows the user to dial required doses from 0.5 to 30 units in 0.5-unit increments.”

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Yeah… but that doesn’t mean it’s doing it accurately… though, realistically… at doses that size how much can it possibly matter

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But other 0.5 unit pen manuals I’ve seen (for Humalog and Apidra) specifically say the pen cannot be used accurately at less than 1.0 unit. So the fact that the Echo manual says you can dose 0.5 of a unit makes me think it must be more accurate than other pens (also the fact that it’s metal and plastic, while the other pens I’ve seen are entirely plastic).

I regularly dose 0.5 of a unit because it drops me by about 1.5 mmol/L (27 mg/dl) and sometimes I dose 0.25 if I just need a tiny nudge downwards. So I think accuracy is still pretty important for people who are insulin sensitive.


I agree accuracy is important… I’m also extremely mechanically inclined and a disciple of my grandfather whos machinery skills changed the course of human history… and my sense tells me that the smaller the dose the less accurately a pen can deliver it. There’s a reason you have to back offf a micrometer before measuring the next piece… to eliminate the slack… pumps do this constantly, pens do not… that’s a large part of why they can never be as accurate

ETA - Qualify statement to say that I agree accuracy is important only with injected insulin

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@Jen, we also use 0.5 unit doses regularly with the Novolog Echo pen.

To be fair, though, we also did it with the fancy Lilly Humalog pen and it seemed to be successful. But that was a long time ago, we switched over a year ago.

To add another factor to the equation: @Eric has talked multiple times about how to increase precision by diluting.

@Eric, do you have some thread links you might want to add here?

We use pens to fill the insulin pump (mainly so that we can save excess, unused insulin in our fridge), but occasionally will give an injection when Samson is high. Ours routinely gives 0.5 unit boluses – but that’s a pretty big correction bolus for Samson and that’s usually when he’s super high and we’re not sure his pump site is working, so it’s already at a point where he’s a lot more insulin resistant and it’s also uncertain how much of the insulin the pump says was delivered is actually in his body. So I have no idea if it’s accurately giving that 0.5 unit dose or not. We assume so but maybe if we were using them all the time we’d find that not to be the case.

It is on my list to write-up a demo and show how to do it.

Diluting will greatly increase accuracy. If you are diluting to 10%, a 1/2 unit of insulin is now measured in 5 units of volume. So you are definitely increasing the accuracy, as long as your dilution is correct.

I have to put some pictures together and write it up.

But just from my perspective, I am not diluting to make it more accurate. I dilute to allow me to micro-dose from a pen or syringe, in amounts like 0.10 units. Being able to take 0.10 units with a pen or syringe is puzzling to some people who wonder why anyone would want to do that. But sometimes that’s all you need. Being restricted to 1/2 unit doses is bad if you want 0.1 units. There is an easy workaround!

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Do you dilute a whole vial for those rare cases? When we were taught dilution we would dilute the entire vial of insulin, so you couldn’t then take a 3 unit dose with a pen, because it would be 30 units… I’m not sure how you’d dilute a smaller portion and keep it sterile? Or you just do this with pen vials?

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I do it several different ways, depending on what I am doing. I would never take 3 units from a diluted vial, because like you said, that would be a ridiculous amount of volume to take.

So I bought some empty sterile vials, and I have put diluent and insulin in those, at a particular percentage which I mark on the vial. I use those vials with syringes and also at times I have used them for some pump experiments for intravenous delivery (higher volume flow reduces the clotting of the cannula).

For pens, I just add the insulin and diluent directly to the pen cartridge, at 10% for whole unit pens (1 “click” equals 0.10 units) and 20% for the half unit pens (1 “click” also equals 0.10 units).

So I have separate pens that are diluted and not diluted. If I need 0.1 units, I can get that from a diluted pen. If I need 1 unit, I get it from a non-diluted pen.

Is that what you were asking?


Also, don’t forget that pen needles are generally quite a bit shorter than syringe needles.

My pen needles are 4mm, and I use that primarily for bolusing. But when possible I use a syringe with an 8mm needle for corrections. Absorption seems quicker with the longer needle. I know @Eric has written pretty extensively about this.

Edit: @Eric I should not post before I have my coffee in the morning. I meant 8mm pen needles and 1/2" syringe needles.


I have 8mm pen needles and 1/2 inch (12.7mm) pen needles. I liked them much better than the 4mm needles.


yes! Where do you get the sterile empty vials? Is that something you can just order online or do you have to pick it up at your Endo office or the pharmacy?

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Sterile and empty vials do NOT require a prescription.

I will look at the name and give you a link. I bought them online.

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Doc, I can send you some 1/2 pen needles if you want to try them. That gives you the best of both worlds.

The ones I have are BD. Good needles!