Is there a difference?

I have a question about syringes vs. pens vs. pumps. I have never used any devise to inject my insulin other than a hypodermic syringe. I’m curious as to if the unit calibrations are the same between all of the administration devises. I’ve taken shots through the U40, U80, & currently U100 insulin types. A U100 syringe is calibrated to 100 units equals 1cc or ml. So if I say I’m injecting 50 units for a basal dose of NPH that is one half of a cc/ml. Then if I say I’m injecting 25 units of Reg for a bolus dose that is one fourth of a cc/ml. Are pens calibrated the same so when one person is talking about doses from their pen or pump is it the same as people talking about syringe injection dosages like me? I apologize for my ignorance, but asking is the only way to learn from experienced people when comparing apples and oranges.

Hi Bill @rs3880 , you and I come from the same era - ancient history for many of the contributors here. As an aside, the syringe I used for decades before having to change to U-100 had an orange color U-40 scale on one side and a green color U-80 scale on the other - easy to use either.

If everyone is talking the U-100 standard which was adopted about 1975, 25 units is 25 units be it delivered by syringe or pen. And the same 25 units of insulin whether the syringe has a capacity of i cc/i ml which would be a capacity of 100 units or the smaller syringes which have capacities of 1/3 ml and 1/2 ml. Some of the lower capacity syringes [the 1/3 ml syringe have scales markings in 1 unit intervals and in 1/2 unit intervals making it possible to administer “finer-tuned” insulin doses. Some pens too can deliver 1/2 unit doses.

Also, insulin is available in U-300 and U-500 strengths useful for people who have severe insulin resistance.

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Thank you Dennis for that explanation that cleared up my curiosity. You shed some light on the U300 and 500 stronger insulin’s that I may need to investigate because I’m needing to take way more than the average dinosaur.

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Tagging on here with @Dennis , a unit is 1/100 of a milliliter and it’s the same for pen, syringe, or pump. The u value is a way to indicate concentration, so u500 insulin is 5x more insulin per unit compared to u100. Cheers.

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I used syringes for about 15 years before switching over to pens. I didn’t think I’d like the pens, and at the time they were more expensive.

As Dennis and Joe have said, the insulin is the same u100. The only difference is in the delivery.

With a vial, you take a long syringe, inject air into the vial, pull out some insulin, clear out the air bubbles, draw up what you need, inject that, and have to dispose of the whole syringe. You can draw as much as you need (depending on the size of syringe) and can even do half units. But there are 1000 units in a vial, and if you drop it (and don’t have one of those handy insulin vial coozies) you can lose a lot of insulin in one accident.

Pens come in boxes of 5, with 300 units in each pen. They’re made of thick plastic, so you don’t have to worry about dropping them. You’re injecting directly from the pen’s reservoir, so there’s no worrying about air bubbles. You screw on a small needle, dial up the number of units you need, press the plunger to inject, cap and unscrew the needle, and only have to dispose of the needle. You can only dial whole units, and there’s a limit (usually about 60 units) to how much you can do in a single shot. It clicks with every unit so you can hear and feel how much you’re getting. There’s a bigger click when the plunger gets to the end of the dose, so you can be sure when you’ve injected the full amount that you’ve dialed. The numbers are also bigger than they are on most syringes. When the amount in the pen is less than you’d give in a dose, toss the pen and get the next one out of the fridge. It can be hard to get used to using a pen at first. It’s a lot bigger than a syringe and it requires a completely different grip. But it’s not bad once you get the hang of it.

Pens used to be more expensive than vials, but enough people switched over to pens that the price started to drop. You’ll have to check with your insurance to see the relative cost. While you’re at it, it’s worth seeing about the price of different types of insulin, which may be different in pen form.

Thank you that info. A very accurate explanation of the pen option. I have some decisions to make now. I’ve used syringes only for 58 years and the thought of change is a little overwhelming sometimes.

It does take some time to get used to it. But it’s largely the same. You’re taking the same insulin and probably the same size needle (there are a bunch of pen needle options, but pens are standardized so any needle will fit any pen) and you’re just setting the dose you need, putting the needle in, and hitting the plunger. The difference is in how you set the dosage and the size of the thing attached to the needle. It’s not as big a change as it may feel, and you’ll get used to it within a few weeks, tops.

The pens are designed to be easier, safer, and more convenient, particularly for people starting to struggle with eyesight, fine motor control, and coordination. You’re turning a big dial that clicks into place for each unit, and you’ve got a nice big plunger button to press. One pen and a handful of needles are a little easier to carry around than a vial and a bunch of syringes, too. But it can feel kind of unwieldy wrapping your fist around a thick pen when you’re used to gently maneuvering a thin syringe with two fingers.

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Humalog pens are available in half units, if that’s helpful; dunno if other kinds may be, as well.

We were taught always to prime the pens, though I know my daughter mostly didn’t bother. It’s more important when starting a new pen, lest the first couple of units you think you’re delivering be air. You can check for and deal with any bubbles the same way you would in a vial, though since you’re not injecting air to equalize pressure in the pen, you’re much less likely to have bunches of air in the first place.

You don’t have to toss those last few units, either, though certainly you can. If you’re willing to take the extra stick, then you can finish off whatever’s in the old one and take however much more you need from a new pen. (You could also steal the insulin from the pen for a pump, if you had a pump.)

And they’re good for the same number of days once opened as the vials are, though if you’re using more than the average dinosaur, that’s probably not an issue for you.

I really like how much longer it takes to fill a sharps box just tossing the pen needles instead of whole syringes. And Paul-Gabriel is right, too, about how much easier they are to dose with. The physical click plus the larger numbers are really nice for those of us whose vision and fine motor skills aren’t what they used to be!

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Very informative srozelle. I am currently taking Novolin NPH and Reg at larger doses than normal dinosaurs. I am however interested in the U300 and U500 versions that have been mentioned here. The pens as you and others have discussed definitely have advantages compared to syringes, but after decades of practice, oh lord I feel old, I have evolved to where I can extract every drop out of a vial…are there any awards or medals given for that achievement…I guess not, oh well. :grin:

It sounds like I have been in a coma for years and now I come out of it and finding out about things I just was determined to ignore. I’ve been in a rut for yeeeears, and hearing things explained and how informed other people on this forum are is refreshing and gives me hope toward change. Here’s a blast from the past. Do any of the fellow dino’s remember using the glass syringes with slide on disposable needle hubs and urine test tape, diastix, and clinitest kits?

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Hi @srozelle. Re sharps containers, I use them for the needles (not the syringes) I use to fill my pump cartridges, as well as for pen needles on the rare occasion I use them. The fill needles with cap are maybe twice the size of own needles, and it took me 3 or 4 years to fill my 1 gallon one. I use a cartridge for 3 days so if you want to go back to math class you could answer this problem:
Assuming pen needles are 1.5 times the length of capped pump needles; and that they are used at the rate of [your number here] per day, while pump needles are used once every 3 days: what is the ratio of pen needles to cap needles that will fill a container, and
(Extra credit) how do you pick out scented candies when you wear a mask while shopping?
(Math was hard for me so both questions made about equal sense🤪.) Have fun.


I’m not quite old enough to be a dinosaur. Caveman, maybe. When I was diagnosed in 1990 (which still doesn’t feel like it was over 30 years ago), we had BG meters. Not very accurate and they needed a full ml of blood and took 30 seconds to get a reading. But they worked.

The hospital had a more accurate meter the size of a breadbox, which they brought in on a rolling cart. Diastix were the backup: if you found yourself over 250, you were supposed to use them to make sure you hadn’t gone low and rebounded. I almost never needed them. The few times I was that high, I knew why.

There was talk at the time about development of a meter that could read your BG through the skin with infrared light. But it was the size of a cash register, ridiculously expensive, and required blood from your veins to calibrate. They were also experimenting with hypospray insulin, where instead of using a needle, pressurized air forced the insulin through the skin. To no one’s surprise, this was unreliable, painful, and caused significant bruising. I knew at least one person from my teen support group who was in clinical trials of one or the other of those, but both technologies were shelved pretty quickly.

Fun to reminisce every now and again. And I’m glad our collective knowledge can help you.

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Bill @rs3880 , like you I injected insulin for many years - 47 until I decided to use pumps 17 years ago. However, I used various insulin pens beginning in the 1970s.

As @srozelle wrote, literature delivered with pens say to prime the pen after attaching a needle. This is necessary to clear the needle hub and pen reservoir of any air - I recommend that you do this pen-priming unless “In-the-Ballpark” food bolus and correction fit your style. One of the reasons I changed to a pump is so I could more accurately deliver insulin.

Hoping to not overload you with information, I’m taking a chance and attaching a link to the American diabetes Association - Diabetes Forecast Magazine - for a while, my name was on the Masthead as an editorial volunteer. These two pages provide description for [most of] the pre-filled pens available - this information may help to when talking to the physician who will write the required prescription.


Excellent, Dennis. Then begins the battle with insurance, which likes to keep me in the prehistoric era. It took 2 years arguing with insurance to finally agree that I needed a CGM. When my doctor first sent a prescription for a certain CGM to my pharmacy, the copay’s were ridiculous and I refused to pay them. I asked the pharmacist what percent the insurance was paying. She said they were only willing to pay $5.00 toward the monitor and pennies on each sensor advising they had recommended I could still use the glucometer, and test strips, so the battle waged on until finally triumph.

I was diagnosed in 1963 and used syringes with those wide gauge needles (ouch!). I carried my kit around with me - always treating my bottle like liquid gold - until I started on a pump in the mid 90s. I have pens as a backup, and while holding them takes a little getting used to it’s not difficult - and while this may not apply to you I imagine they may be easier for people with arthritis or issues grasping things, as well as vision issues. And portability is much better - you can tuck your pen safely in your pocket - no bottles to worry about!
Personally I’ve found it best to leave the insurance to the pros (or device reps in the case of durable equipment) so let your doctor’s office do the legwork. If more than a prescription is needed their office will need to provide it and they’ve likely done it many times before. I would hope it wouldn’t be a big issue - it’s simply a different way of injecting insulin (vs infusing with a pump) and the cost difference of going from bottles and needles is much less than switching to a pump, or starting on a CGM - although there may be other considerations with your plan.

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