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It’s a dilemma just about every insulin-using person with diabetes has faced, for many a reason: What to do about expired insulin?

Take the mom of a child with diabetes who realizes at day 28 of an open insulin vial that they’ve barely used half of it, but have reached the listed expiration date.

“It feels so wasteful,” that mother explained.

Or the young adult with type 1 diabetes (T1D) struggling mightily to afford their insulin, so is tempted to stretch it out way past the formal cut-off date.

“The longer I can make it last, the less chance I go broke,” that young adult told DiabetesMine.

Or even sometimes a well-known endocrinologist, who finds himself faced with using expired insulin or none at all and chooses the former.

“Funny you ask,” says Dr. Stephen Ponder, a pediatric endocrinologist in Texas who lives with T1D himself. “A year ago I forgot my rapid-acting insulin and found one vial in my office fridge. It expired in 2016 (3 years prior). I used it, and it worked as expected. Any time one does this, of course, we take a calculated risk.”

The temptation is real — be it for cost savings, convenience, or just plain not wanting to waste a liquid that quite literally costs more than its own weight in gold. Insulin users often find themselves questioning expiration dates.

Yet determining whether insulin is still good is nowhere near as simple as sniffing a milk carton, so how do you know?

DiabetesMine took a deep dive into the big questions related to insulin expiration dates: when it actually goes bad, and options for disposing of expired insulin when necessary.

Manufacturers actually confirm that insulin has two separate expiration dates:

  1. The first is the one printed clearly on the product. This is the date that the insulin pen or vial, so long as it is kept refrigerated within approved temperatures, is assured by the manufacturer to be usable.
  2. Secondly, there’s also the amount of time from which the pen or vial is first opened for use. This takes a bit of memory and math on the part of the user: Typically, insulin is effective for 28 days after opening, with a few types lasting up to 40 days.

Clearly, that means users are supposed to mark the date they open a vial or began using a pen, and then keep track and discard it after 28 days.

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“Multiple studies are conducted to determine the length of time insulin can be manufactured, distributed, and used by the patient,” says Michael A. Dobbins, a principal research scientist at Eli Lilly. “These expiration dates ensure that the drug meets established quality standards on the date of expiration.”

The insulin companies do this testing to assure that their products comply with the 90-95 percent potency guidelines required by the Food and Drug Administration (FDA).

So when expiration dates hit, It’s not that the insulin doesn’t work, it’s all about the potency,” says Michael Castagna, CEO of inhalable insulin manufacturer MannKind.

For instance, he says if a person may need 4 units of insulin to cover some food, they can be pretty well assured of accurate dosing when insulin is within the expiration dates. Once it is past those dates, you just don’t know for sure.

“So while you give yourself 4 units, you could actually only be getting about 3.6 or less,” he explains.

“Insulin users can think they are being accurate with their carb counting and with seeing blood glucose values on a CGM (continuous glucose monitor), when you may be getting variability in dosing,”

How and where you keep insulin — from the favored refrigerator butter compartment to bags and purses — can have a huge impact on how effective one’s insulin might be. This is mostly about temperature, assuring that insulin doesn’t get too hot or become frozen.

D-Mom Shelley Spector, who has T1D herself along with her daughter diagnosed about 15 years ago, admits to using expired insulin “all the time” but with a caveat: She’s careful about storage.

“I am on a vial now that expired in 2019,” she says. “We have such a backlog of insulin, I cannot recall the last time we used non-expired. I don’t want to waste it. It’s like gold to me.”

Spector is careful about keeping her insulin — even when the vial is open — in the fridge. She believes this helps assure the potency of the insulin even after expiration dates.

Her daughter prefers pens, and Spector says she has to be more careful about those, but still, they don’t worry too much about printed expiration dates as long as the insulin has been stored properly.

Jennifer Smith, a diabetes care and education specialist (DCES) at Integrated Diabetes Services in Pennsylvania who has T1D herself, points out that the manufacturer’s expiration dates are there for a reason, but she also told DiabetesMine: “There are soft edges around it. I’ve pushed it myself. I store it entirely in the fridge. Even an open vial. Keeping it at a more consistent temperature helps me feel more confident using it beyond the 28 days.”

Smith points out that “room temperature” can be quite variable, which is why a fridge is a good option. Typical fridge temps range from 36° and 46° Fahrenheit, so you know the insulin is sitting at not just an acceptable, but also a consistently acceptable temperature.

“I ask people where they store their insulin, and sometimes I have to point out things like, if you have an older fridge and you keep it on top of it, there could be some heat it is exposed to up there,” she says.

Allowing insulin to get too hot or too cold can be a reason to discontinue use, even if you are not at your expiration date yet, she says.

Extreme heat, she says, such as would come from, say, leaving a vial in your car in the summer heat, should be a reason to toss it, she says. And when it freezes? That’s another must-go moment.

But how is a person to know if it got too hot or too cold without extreme heat or freezing?

“It’s more the heat that degrades it than the cold, other than freezing,” Smith says.

Her advice? Try it and see. “You’ll know right away if it is not working,” she says. And when in doubt and able to, just err on the side of caution and toss it.

But there is one insulin that loves the freezer: MannKind’s Afrezza inhaled insulin can be frozen for an extended period of time.

“You can freeze it for years and it’s fine,” says Castagna.

When not frozen, though, inhaled insulin has some expiration dates as well. Its packaging protects it from light, but once that packaging is open, it’s good for a month. Once you’ve pierced a cartridge (from inside that box), you must use it within 3 days, he says.

The Afrezza inhaler must be replaced every 2 weeks as well since residue can build up on it (and keep a full dose from getting through).

Castagna says March and April 2020 were the company’s best sales months ever, something he wonders could be connected to the pandemic and folks looking to stock up, since the freeze option may give people more confidence in stockpiling insulin.

Castagna says he suggests people pay close attention to expiration dates, but adds, “I collected expired insulin to help people in Africa and it worked. Something is better than nothing.”

Details on insulin storage

Read our in-depth primer on insulin temperature control here.

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Many find themselves asking this question when insulin “seems like it’s just water” and has little to no effect on blood sugars.

That potency issue is has been explored in numerous studies in recent years, and while insulin manufacturers and researchers have found that the supply chain isn’t a regular problem, they still encourage pharmacies and distributors to carefully follow protocols in shipping and storing insulin.

Unfortunately, insulin does not automatically turn cloudy or look any different when it’s going bad. In some extreme cases, cloudiness or crystals may form in the vial. That’s a sure sign that the insulin needs to be replaced unless of course, it’s an older form of long-acting insulin known as Humulin, Novolin, or NPH that is made to be cloudy.

Ponder, who points out that the best choice is always to use insulin that is within expiration dates, dreams of a time we can easily test our insulin for viability. Like the milk drinker checking the date and then sniffing to decide, he would love for people using insulin to have an easy litmus test of its potency.

“I’ve always wished Duracell would invent an insulin tester like what they did for batteries,” he muses. “Maybe even some home test kit that would turn colors if insulin was over a certain amount denatured.”

Until then, insulin users will continue to face down dates and sometimes push past them.

“It’s hard to just toss a vial when you find one in an old purse,” says young adult with T1D Elena (not her real name). “It feels like throwing away hundred dollar bills. Crisp ones, too.”

The reality is, many do use insulin past the expiration date.

For Elena, who’s had T1D for 19 years and struggles at times to afford co-pays, using expired insulin “is way better than rationing,” she says. She stretches each vial as long as she can.

“I admit, also, to finding one in a purse and just thinking, ‘Hmm, I’m going to try this,’” she says. “It was fine. But I also checked my blood sugars a ton more while using it.”

Which is sage advice. Should you choose to stretch insulin, experts say (while pointing out that this is off-label use), you should amp up your glucose oversight.

If you are not going to risk using expired insulin, the issue then becomes what can be done with it.

“When I think of the people who cannot afford [insulin] or struggle to get it, it just feels wrong to toss it out,” Spector says.

Groups and programs like Life for a Child and Insulin for Life cannot, by law, accept expired insulin.

Other options do exist, though.

  • Many doctors and clinics are unable to take any donated insulin once it’s opened or at all, given the uncertainties of whether it’s already been compromised by the time they’d receive it. But this policy does depend on the particular doctor’s office or clinic, so it’s definitely worth calling around to ask.
  • Local animal hospitals may also accept expired insulin, depending on their policies and where they are located.
  • Private hand-offs are also possible. With the insulin affordability crisis in America, a growing black market has materialized where people within the community regularly donate various types of insulin to each other directly, or through grassroots efforts. The #insulin4all hashtag on social media is full of requests, as well as networks of people who focus on getting insulin donations to those in need. While this isn’t technically legal, given that prescriptions should be not shared with those who are not prescribed, it is common within the D-Community, and a December 2019 study points out providers should be aware of these underground networks, to understand their patients’ resources and potential risks.

Insulin is a precious, life-saving substance, and we’re right to think hard before throwing it out.