• Guest - w'd love to know what you think about the forum! Take the 2025 Survey »

Insulin Pen Query

J

Josh_Briggs_18

Member
Messages
10
Hi,

I'm currently studying Product Design at Nottingham University and have a brief that involves designing a product that aids the life of those with diabetes. I'm currently going down the route of an insulin pen re-design but I have a few questions that I have not been able to find the answers to online. I was hoping I could receive some help.

Firstly, I'm wondering why insulin pens are not smaller than they currently are, I've seen that the average length of a pen is around 150-170mm which is pretty big in my opinion. I was wondering if there was any particular limitation as to why this is so.

Secondly, how does the insulin dosage system work. Ive seen that the pens come in 150 and 300 unit cartridges. Is a cartridge used per day or does it usually last longer than that? Could it be an option to do a pen that is just 100ml in cartridge size for people going on nights out or is this too little?

Thirdly, how do you figure out exactly how many units of insulin you need throughout the day. I've attempted to look further into this and have found several mathematical formulas that aid with the calculation but still, surely this is a bit of a pain.

And finally, what do you take out with you on a day to day basis e.g. testing kit, pen ,etc. I am unsure whether you have to have a test kit and pen or you can just take out a pen.

Hopefully you understand my questions, and sorry if I have been a little vague, I still only have a very basic knowledge of this subject area. I'd be extremely appreciative of any feedback!

Thanks,
Josh Briggs
 
Last edited:
Hi @Josh_Briggs_18 - can I suggest you read the website that this forum is a part of and the Diabetes UK and JDRF websites, plus contact the pen manufacturers regarding your questions? You may also want to reach out to a hospital diabetes clinic or a local person with diabetes who can show you why things are the way they are.
 
Dude!

We kinda touched this the other day?
The cartriges come in a standard volume size regardless of insulin strength, U100 U300 & such like. (There is also a U40 for dogs.)
The size of the cartridge dictates pretty much half the length of the pen.. The other half with the ram mechanism & dial up dose ratchet/linkage system that drives delivering a measured dose dictates the length approximately of the other half..
Then add another 15 to 20mm for the cap to cover a needle.

Depending on a certain diabetics insulin needs, factoring insulin resistance, insulin to carb ratio & dosage for the amount of carb intake? & the sort of diet regarding the amount of carbs, You are asking how long is a piece of string with how long an insulin cartridge lasts. Though, they normally have a use life of about 20 odd days before the insulin goes off. (Pending on environmental climate.)
You have pretty much discovered on here no Diabetic can tell another how much insulin to use..

Any insulin dependant carries a meter, insulin & hypo treatment of choice...

Lol. @tim2000s i was just about to tag you in...!
 
Josh Briggs 18 hi don't know if I can help alot regards size of pen I think most pens are made this size because of the size of insulin cartridge both my pens are prefilled and hold 3ml cartridges so just throw away when empty also how long the insulin lasts depends on how much your injecting so many units per day 1pre filled pen lasts me about 2 half days roughly regards working out how much to inject I work it out by what my blood sugars are doing when I test with meter and adjust insulin accordingiy that's just how I do it others probably do it there way which ever way that is more members will probably get back to you on this subject hope this may have helped abit let me know?
 
More help for Josh..!

 
Hi, @Josh_Briggs_18 , one reason for the size, quite apart from vial and ram size, might also be the ergonomics of it.

I inject in my stomach/side of stomach, so I'll just pull up my jumper a bit, pull a bit of my t-shirt out and inject discreetly in the exposed skin. I can wrap three fingers round the pen about half way down, leaving my thumb tip to press the plunger, and there's still enough length left at the bottom of the pen to negotiate past the rumpled jumper/shirt and generally see what's going on. Remember I'm putting a needle inside myself so I want make sure I've got good manual control of all this.

Now, let's imagine you design a smaller pen. Conveniently enough I've got a Swiss Army knife sitting nearby which is about half the length of my pen and about as wide. When I grip that and pretend it's a pen, I find my hand covers all of it, I've nowhere to put spare fingers, my hand is so far up the pen that I'm having to push the plunger with the base of my thumb not the tip, unless I open my palm up in which case I'm not holding the pen as firmly, plus I can't really see the sharp end at all because my hand's so far down, which isn't going to help at all getting past the clothes and seeing where the needle goes.

It seems very much like trying to use those mini-chopsticks you get with supermarket sushi.

It just doesn't fit my hand.
 
I would like a insulin pen that would BT the time and the size of doses to my phone app diary and/or BG meter.
 
Oh. Too hot and too cold for your insulin alarm built into the pen would be nice.
 
eventhorizon said:
I would like a insulin pen that would BT the time and the size of doses to my phone app diary and/or BG meter.
Click to expand...
There are a few of those in th eplanning:

https://www.emperra.com/the-prototype.html
http://www.companion-medical.com/products.html

@Josh_Briggs_18 - I think what you're missing is that Insulin Manufacturers want to make as few devices as they possibly can. Each additional device comes at a cost to set up some form of manufacturing line. They are therefore not going to produce multiple different lines of product with different physical characteristics.

You have to consider the users of these products. They stem from parents of very young children to old people with significant mobility and sight problems. There is a lot of cost in making individual products for each of these, so instead they try and capture 90% of users in as few as possible.

So while you might look at a pen and say "That's large and unwieldy" (for most people it's not really, and it has the size and look enough of a pen such that many of my colleagues have picked a Novopen up off my desk to write notes with, and got a surprise), for those with hand issues (and many T1s and T2s do have these), that size is needed in order to use the thing.

Going back ten years, all the cartridges for the reusable pens were 1.5ml, not 3ml, but as they are used for T2s as well as T1s, and T2s generally require much more insulin, the size was changed to get more than a day out of a pen. There are many factors affecting the design. The really key ones are about usability for those with impaired mobility and site and the amount of insulin they can hold. I'd strongly recommend talking to the insulin companies that provide the pens to get a much better insight into the reasons for their design.
 
I carry 2 pens. Different types of insulin. 3ml cartridge in each. One type lasts me 10 days. The other 30 days.

3rd. An individual diabetic's insulin requirement will be fairly unique to them depending on their type, type 1 or 2. Their size and weight. Their diet and

4th. I never go out without 2 pens. Blood Test device. Glucose tablets.

The cases that pens and test devices come with are usually really badly designed.

I test blood maybe 5 times a day and inject 4 times a day so ergonomics is everything. Blood test- Get it out of my bag. Get it out of its case. Find somewhere to put down the meter. Load test strip into meter. Stab finger. Apply blood to test strip. See result. Put it all away again. Then out with the correct pen. Using the wrong pen could literally be life treatening! Dial a dose. Is that the right dose?. Take pen cover off. Take needle cover off. Bear a bit of stomach or leg or somewhere. inject. Press plunger. Is that the whole dose. Did I press hard enough? Put needle cover on. (Bloody tricky in poor light.)
Pen cap back on. Pen back in case. Case back in my bag........
Now imagine doing that in a coffee shop. Easy right? How about standing at a take away van at glastonbury at night in the rain?

Ergonomics is everything. Design for ergonomics.
 
Hi,

Thank you so much for your reply, this is what I've been really wanting and your reply will be a huge help to me. Yes, I think ergonomics is probably the route to head down with the fact that recent feedback has shown me there isn't much point re-sizing the pens. You seemed genuinely happy to help me and I am extremely appreciative.

Thanks for your time!
 
Jaylee said:
More help for Josh..!

Click to expand...
Hi,

Yes I remember! You've been really useful to my project!

Okay, I understand! Sorry for being vague and probably asking seemingly simple questions, I'm a noobie to the field!

The video will be extremely useful and is exactly what I was looking for!

Thank you very much for your time!
 
Hi, thanks for your reply, I appreciate the time you've spent to write it and provide me with as useful feedback as possible! Yes it really does seem like there's too many issues with resizing the pen for the sake of a few mm. I agree with you massively that a smaller pen would make things much much harder and to be honest hadn't really considered such barriers until you mentioned them. See us designers only see the product side of things, which is why its really helpful to work with someone that knows what theyre doing! And its nice to be provided with really helpful feedback on things that could go wrong! Thank you very much for your time!
 
Happy to assist further if that would be useful- please PM me for my email address.

Edited to remove email address.
 
Last edited by a moderator:
Hi, I have a savvio pen, which is quite a bit smaller than the novopen. Its kinda almost cute...it would be nice to have one small enough to fit in a going out handbag without having to take a duffle bag as well....
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn More.…