Refilling insulin pens

Has anyone ever tried to refill an insulin pen with different insulin? I know it’s not the greatest of ideas, and probably an even less great idea to fill a rapid acting insulin pen cartridge with NPH or regular, but I’m curious if it’s been done, tips for the filling, etc. Pumps are by far my favorite followed very distantly by pens. I’d like the discretion of a pen with the ease of obtaining NPH and regular. Thanks for the insights!


Now you have me very curious. Why if you are using your pump would you want to supplement with a pen? The pump should supply you with continuous background coverage and NPH would be overkill.

I don’t know about these “newfangled” pre-filled insulin pens - since the late 1970’s I used pens into which cartridges of insulin (Regular and NPH, and beginning 1996 Humalog) would be inserted. It was easy and convenient to have a pen for both background insulin and meal/correction bolus. I tested, evaluated and used this type pen for many years before switching to pumps. I don’t know if those cartridges are still available; I’ve still got souvenir pens including one that has a BG meter built in.


It looks as if my earlier reply went off into space - the only part that remained was my “tag” under your posting; I’ll try again.

While using a pump, I can’t imagine why on earth you might want to have a pen with either NPH or Regular; your pump basal rates [good pumps allow you to set different rates for as many as 9 timeframes during the day] making NPH or any other “background” insulin unnecessary, and the pump will calculate and deliver a meal or correction bolus based on your carb ratios and the carb count you enter. Virtually error free and a pump can be very discrete. I agree that a pen might be useful for correction bolus if you suspect that your pump might be malfunctioning.

That said, there are ways to do what you are thinking with pens but I don’t really recommend. I started using pens and evaluated new models in the 1970’s long before these “newfangled” prefilled pens existed. In those days insulin came in the traditional 1,000 unit vials [that is after the standard became U-100 and U-40 and U-80 were phased out] and in 3 mil and 6 mil cartridges. The procedure was inserting a cartridge in a permanent reusable pen and screw on a needle every time insulin was needed. Those cartridges could be refilled although it wasn’t recommended.

I haven’t used a pen since the day I started pumping and I hope I never need to go back. I think I still have a couple of those pens about, including the last one I used that included a BG meter and displayed the time elapsed since the last injection - took some of the “did I or didn’t I” guess work out of wondering if I took a shot at the restaurant.


Thank you, Dennis. Good luck in your continued blessing of pump discretion. Perhaps I can find the older pens you speak of in my experimentation.


I’m not sure if this is exactly of interest to you, but since you mentioned looking for the older pens Dennis was talking about, I thought I’d share that you can buy pens that are re-loadable with cartridges (instead of the disposable pens).

Here is a link:
Novo Echo Insulin Pens

I have a few of those cartridge pens around from when I was younger. My doctor refers them as kid pens. They max out at 35 units and go in half unit increments. I prefer the prefilled pens that I use now to those. The cartridges are glass and can break if they are dropped and land strangely and the pens themselves are metal and substantially heavier than my completely plastic prefilled ones. Also I don’t have to twist the plunger back to get a new cartridge. Another drawback was If I accidentally went to far I had to set the shot back to 0 and redial instead of dialing it back to the correct dose.
Ive never heard of refilling a cartridge or pen but I suppose it could be done. You would need something to reset the rubber plunger though because it it not attached to anything. If you are successful you might be able to create a recycling thing where we refill our insulin shots rather than throwing them away