Diabetes Disaster Response Coalition

So, I found this from the DDRC about insulin storage:

What struck me particularly was this paragraph:

“Insulin contained in the infusion set of a pump device (e.g., reservoir, tubing, catheters) should be discarded after 48 hours. Insulin contained in the infusion set of a pump device and exposed to temperature exceeding 98.6°F should be discarded.”

I don’t know about the rest of you, but I’ve been prefilling four cartridges at a time (one bottle’s worth) for years. And I continue using the insulin in my pump even after I’ve been riding my bike for hours in 99 degree plus heat. (I’ll change my cartridge if I get a bunch of highs and my injection site is good, but that has rarely been my experience.) My most recent HA1C was 5.5 so I don’t believe I’m out of line in doing these things.

One of my doctors used to tell me I knew more about my diabetes than any doctor or expert and I guess I agree with him in this case. Anyone else find this?

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When I first started using a pump nearly 30 years ago I filled my cartridge with a week’s worth of insulin. I also pre-filled a few cartridges and kept them in the fridge - that is frowned on now too. I’ve been using Omnipod for a year now and the pods expire after 3 days but I can’t say I’ve noticed any difference after day #2.
I wonder if the newer formulations are more sensitive than the old ones and thus the extra caution? That said, I think the warnings err on the she of caution for safety’s sake, so if people do push it and have problems at least the powers that be can say “well we warned you…” - but that is pure speculation and personal opinion on my part.

Today it’s 97 degrees and it’s been this hot for several days. My pump is in a pocket next to my skin so it’s probably a few degrees hotter.
I filled my cartridge 6 days ago and stuck it in my pump. I always fill my cartridges to the max and use them until they’re dry.
My BG is totally normal at 100 mg/dL, and it hasn’t gone above 250 all week. My A1c was 5.7 a month ago.
So according to that article I should be in DKA or something right now? I wonder who or what they’re basing their research on because I don’t think anyone with T1D has actually seen that reflected in their BGLs (unless they actually cooked their insulin or something).

Also, I’ve used opened pens 2-3 months after taking them out of the fridge and they’ve been just fine. But then I also restart my cgms…. I break a lot of the rules.

The source was published in 2018, 5 years ago…. Could be outdated, but I wonder what would’ve changed in that time besides insulin prices?

Good point about warnings erring on side of caution- I just wish someone had told my parents that when I was diagnosed because for years my dad would panic each time the fridge shut off because he thought if the insulin temp changed by 5+ degrees it would spoil.

Oh, yes, that’s right! My first pump was a Disetronic with a 3.15mL cartridge. You were supposed to either fill it to 150 or 300mL, whichever lasted… was it 6 days? I always filled my reservoirs to 300 until one of my new pump educators convinced me not to let it run for more than 3-4 days (which sometimes stretches to 5, depending on my activity.) As I mentioned, I rarely have problems with this, although I vaguely recall some pretty sketchy day 6s back when. My most recent new pump educator tried to convince me not to prefill, but…


Mark @MarkCK the manufacturers of analog insulin include on the package information sheet that insulin that has been in a cartridge for more than 7 days should be discarded - I suspect that the 7 days includes a margin of safety. The 48 hours may apply to rDNA formulations which have not been recommended for pump usage for about 2 decades.

I live in Florida where it is kinda warm year round and haven’t had any noticeable insulin deterioration when bike riding for 6 hours three times every week and when hanging out on the beach swimming, walking, and reading [under an umbrella]. Insulin these day is very durable when compared to the stuff extracted from animals - which I used for 20 years before rDNA was developed on board the USSL in the early 1970s.

Ah, a fellow cyclist! I wish I could ride 6 hours straight…my hands would probably be numb up to my elbows if I did.

Like you, I remember the good old days of pork NPH in the 70s. Then NPH in combination with a shot of Regular in the mid 80s, then three or four shots of Regular in the late 80s and 90s… OK, so not so good old days, but better than the alternative.

As I mentioned, I fill four cartridges at a time - one set at work and one at home. Taken together they last me about 4 weeks. I don’t believe I’ve experienced any problems in the three or so years I’ve been doing it.

@Dennis @MarkCK since you enjoy cycling did you know there is a team of professional riders with Type1? They tried out for the Tour de France in 2021 but did not make that race. They do compete in other races thoigh. Moderators, I know I am getting off topic. I promise that’s all I will say here😊.

Oh Mark @MarkCK , the six hours spent “on my bike” were not all in the saddle - my skinny seat would ache too much, and like you my hands would fall asleep - I’ve been accused of giving funny and-signals by people seeing me shaking my hand over my head trying wake it up. There is a chain of islands in the eastern Gulf just off the coast where I’d ride - I know every shady spot tstop, snack, eat lunch and read my Kindle or take a cooling dip. Insulin pump always in the heat.

I began that riding regimine 13 years ago when I retired as I reached my 70s, but have had to give up riding two years ago because of balance issues. Just gave away my bike this month.

Sorry to hear about your biking troubles. I’ve been riding pretty much since I was a kid. I mostly do trail riding on a hybrid. I have a road bike, but I never liked road biking as much as trail riding, so it mostly sits.

Anyhow, I looked at my Novolog instructions sheet after reading an above comment and I didn’t find anything about how long it can be kept in a reservoir. (I admit I may have missed it. Such tiny, tiny print… If anyone else finds it, feel free to share.) I did find this:

"How should I store NovoLog? …
All unopened vials:
Unopened vials should be thrown away after 28 days, if they are stored at room temperature. (Apparently they can be kept at refrigerator temperatures forever because it says nothing about that other than they should be kept at 36° - 46°F.)

After vials have been opened:
…can be stored in the refrigerator at 36°F to 46°F…or at room temperature below 86°F.
Throw away all opened NOVALOG vials after 28 days, even if they still have insulin left in them.
If using NOVALOG in a pump, throw away all opened NOVALOG vials after 19 days. (You’re kidding, right? Although this sort of, kind of speaks to how long it should be kept in a reservoir.)"

In the fine print, it says, “Change the NOVALOG in the reservoir at least every 7 days or according to the pump user manual, whichever is shorter.

Do NOT expose NOVALOG in the pump reservoir to temperatures greater than 98.6°F”

So those of you involved in this discussion (including me, obviously) are all doing it wrong according to Hoyle.

hi @MarkCK I suppose it seems that the literature included with the medicine is saying one thing and your experience is saying something else… This is a case where the manufacturer is right and you are right at the same time for different reasons. I support engineering for (research and manufacture) sterile biological pharmaceuticals so I’m speaking from 29 years of manufacturing and quality experience.

All pharmaceutical literature relating to storage requirements are based on stability data from controlled environments and represent (typically) either 1 out of a million or 1 out of 100 million certainty. Put another way - NOTHING HAPPENS if you have 100F insulin for 4 days… usually. The literature says if you obey the discard rules then you will NEVER EVER have insulin efficacy degradation. When the degradation can include serious injury or death, then most pharma go for the certainty of 1 out of 100 million.

quick example: Milk. Milk does not magically go bad on it’s expiration date, every time period after the expiration date, your chances of sour milk go up by about 2^n (two to the n power where n is the time scale, standard, or duration) until at some point, there is a 100% chance of bad milk.

So are we all doing it wrong? yes and no. we are playing, quite successfully, in a margin outside the pharma acceptable risk of 1 out of 1 million certainty. if you have ridden your bike 1 million times, you are very likely to have spoiled insulin 1 of those times. if you ride 7 days a week, that’s about once in 2 thousand years of bike riding.

In my opinion, please don’t get hung up on the binary good/bad do/don’t from the literature set. Your experience is representative of what we all see. The risk is infinitesimally small… unless you plan on living 3000 years.

as far as medicine in contact with plastic, Lilly and Novartis could give a darn about what kind of reservoir and they are not required to include stability data for someone else’s reservoir or pump. That falls on the plastic reservoir manufacturer. Thingks like reactivity, carbon dioxide infiltration, oxygen infiltration, “leachable” chemicals from the plastic all fall on the reservoir manufacturer (typically a subcontractor to the pump manufacturer) and NOT the insulin manufacturer.

In the USA, there are extremely strict regulations on responsibility and testing, and this is a very large part of why change comes very slow, and are expensive. However, it is necessary for limiting errors and risk to patients. The EU and Asia can develop their own regulations but most simply copy the US standards.

most folks using insulin have never read the literature. you are quite detail oriented and would make a good engineer.


And, in fact, I am an engineer. :wink: I posted that PDF up there because it was one of the few pieces of officious information I found on the time you are allowed to keep insulin in the reservoir. After my last new pump educator told me I shouldn’t preload cartridges, I wanted to know why. (Engineer.) And you know what? I still don’t know why. Your comment is as close as I’ve seen to an explanation of why.

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nice to meet you. @MarkCK ok so lets cut away the temperature stability for insulin Now we are talking about insulin in contact with plastic. so on top of the 1/1000000 fairly standard insulin stability data we have to account for (add or demerit) degradation of insulin as a result of contact with plastic.

Insulin in contact with plastic is typically exposed to extra degradation from carbon dioxide (changes the pH) and by oxidation, and in many cases increased exposure to light radiation, and many pump stability requirements are done with vigorous agitation to simulate movement. So in a reservoir, it is typically more stringent than leaving open insulin out because it is subject to more attacks.

Probably the pH changes are the biggest risk because insulin is a really tough molecule. Plastics are really bad at carbon dioxide protection.

Crystallization of insulin in reservoirs and tubing is a function of the plastic chemistry as well and (I don’t have real-world experience here) can be as big of a threat as carbon dioxide. There are papers on insulin adherence to plastic on NIH and other research web sites.

I personally don’t prefill reservoirs, if you are getting good results in what you are doing I would just keeping doing it.

The word I needed to find the research was ‘adsorption’ [binding]. Having recently switched to Tandem, I wondered why the reservoirs contained bags as opposed to the plastic Medtronic reservoirs. (Although you can’t see the bags, you can hear them filling.) Perhaps this explains it.

“It was seen that the adsorption [binding] rate of insulin to PVC set was 57% and PP [Polypropylene] bags is at most 5% at the 24th hour.” (Nursel Sürmelioğlu, Merve Nenni, Ahmet Fırat, Kutay Demirkan, Dilek Özcengiz, “Evaluation of regular insulin adsorption to polypropylene bag and polyvinyl chloride infusion set”, [nternational Journal of Clinical Practice [Volume 75, Issue 4]) They explain that this binding rate was a stable 5% at 4, 12 and 24 hours if I am reading this right. If it’s stable over a day, wonder what it was at 4 weeks? Also, note the huge difference between PVC and Polypropylene. Fascinating…

Most of the research seems centered around the infusion tubing. This is really interesting.

“This adsorptive [binding - to the plastic infusion line in this case] insulin loss is greatest within the first one to two hours of new insulin infusion line use, where typically only 20%-80% of the desired insulin dose is delivered.Insulin adsorptive loss is much more significant where low concentrations and flow rates are used…” (Jennifer L. Knopp, Kaia Bishop, and J. Geoffrey Chase, “Capacity of Infusion Lines for Insulin Adsorption: Effect of Flow Rate on Total Adsorption”, Journal of Diabetes Science and Technology, Volume 15, Issue 1)

And they told me that the reason it’s such a fight to get a new infusion site to work was because of absorption in the skin!

If I understand all this correctly, the binding occurs at the beginning of contact. This suggests to me (although I only have experience to back it, which is not scientifically acceptable) that it should be relatively stable after initial contact. I wonder if there is a longer term study on this somewhere.

News to me on getting new sites to work. And I don’t know that I’ve ever noticed any chance in my numbers after a change [caused by less absorption] unless I picked a site with scar tissue.
But as was suggested above - we see how these things apply to ourselves. Thank you for your research.

Thinking on it, it’s probably more a problem of site absorption in my case like they said. I often have trouble with the first few hours of a new site, which is far too long to blame the tubing based on three different studies I found. Still, it’s interesting how much the tubing can bind to the insulin.

This study (again looking at tubing) says, “Once equilibrium between the insulin binding sites and solution is attained, insulin delivery becomes consistent.” (View of Effect of Tubing Flush or Preconditioning on Available Insulin Concentration for IV Infusion: A Pilot Project | Canadian Journal of Hospital Pharmacy) This makes sense - once the insulin in contact with a surface and binds to that surface, the bound insulin should create a barrier between the surface and the remaining of the insulin. Which pretty much negates that argument as a reason for not wanting to prefill cartridges after the first hour or so.

So the reason probably has something to do with the properties of plastic vs glass as a container as joe suggests. I would imagine if they could effectively ship insulin in plastic containers, they would because it’s got to be cheaper than glass. So (ignoring my anecdotal evidence) I still haven’t found the reason why you shouldn’t prefill.

I confirm the “new site” thought, although the “study” I did was small - only me. I recently changed the type of infusion sets I’d been using for several years, with both Tandem and previously with Medtronic, from 30 degree angle insertion with 13 mm cannula to 90 degrees [experimenting] with 6 mm and 9 mm cannula. I noticed that on some evenings my BGL would be much higher than expected so I began marking these events - to not much surprise, I found a correlation between my “highs” and change of infusion set.

No, unlike you and @Joe, I’m not an engineer although my last 25 years of employment was with a significant engineering and design firm. My job was making certain that classified information remained classified.

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@MarkCK @Dennis my site changes ALWAYS results in high bs. I am super sensitive and my body makes a lot of histamines. Any irritation and I get localized inflammation. Bug bites scratches mold touching cardboard that’s been in an attic, I need to wear a tyvek suit and a respirator to roll up a carpet. Anyway a histamine reaction and the localized inflammation happens at a site change too. When I get that inflammation, I get very poor insulin response until that inflammation is reduced. I’ve used cold packs, hot showers, and general exercise with varying degrees of success. Even a pen or syringe causes inflammation and I need quite a lot more insulin when I was on MDI. The hot shower actually works the best for me. Cheers!

Have you ever tried Benadryl - typical or oral?

No I can’t take benedryl unless I have the next 24 hours off from thinking or general consciousness. I take Allegra and nasal steroids for seasonal allergy.