My daughter did a project in her high school chemistry class on the entire process, describing the steps involved - I don't have that paper handy, but if a high school student can work it out it's probably available elsewhere. She later told me that this project was part of her post-apocalypse-family-survival-plan;)

I share these sorts of worries with you. It's hard.

Like in Texas earlier this year. (Though I suppose it was cold enough you could stash stuff outside…). I wonder if there any teeny little thermoelectric coolers that you could keep for an emergency and run off a bunch of batteries…

Yeah, in theory you can stash stuff outside, but that also isn't as simple as it sounds. While I take some issue with the milk analogy below, in this case, I think it fits. Imagine you have a gallon of milk. You lose power. You go stash it in the snow. Okay, it's kept "cold" for some value of cold. That "some value" matters, because with this gallon of milk, you can't smell it to see if it's spoiled, and if something goes horribly wrong, you die. It's not a binary thing as it sounds immediately. "Cold in the snow" is not the same as "kept at the same value I can control exactly in my fridge."

(It is also true that it is not the case that if it is not continuously absolutely refrigerated, it immediately goes bad, which is one reason why the milk analogy gets strained. Milk expires far, far faster, and in a more binary way than insulin goes bad... but freezing it is extremely bad, so... analogies are hard.)

https://www.bestbuy.com/site/cooluli-classic-0-1-cu-ft-mini-...

Runs in 120v, 12v and even 5v (Eco) mode.

In a pinch I would say a 12v based battery setup should keep something like this running for a while. A few of my emergency power lithium battery packs had cigarette/car ports on them.

That may work for some things, but freezing insulin destroys it.

But if you can’t buy more insulin then that’s a real problem.

My wife needs specific immuno-depressants to keep her alive (or at least not drastically decrease her health) and since we live in France it is not a problem.

When COVID hit I had real concerns about the manufacturing keeping up, but also about other mechanical devices she needs. These were at risk because they are manufactured in a normal factory (non-critical state infrastructure kind). Everything was fine but these are the moments you realize how reliant one is on technology, supply chain etc.

It would almost certainly be more of a hassle than getting it from a pharmacy, and purification is probably a tricky step, but I think we're just a decade or two from this potentially becoming a reality.

Would be incredibly egalitarian and empowering to individuals.

I understand the issues that come with dependence on pharmaceutical companies, but this is what they do. In today's world we are highly dependent on supply chains and that includes both toilet paper and insulin.

Expiration dates vary wildly based on a number of factors, which you probably know, but for completeness: opened vs unopened, refrigerated vs non-refrigerated, brand to brand, etc.

It is true that it becomes inactive over time, but those rates vary. And people know that manufacturers put expiration dates based on liability. Yeah if it says that it expires after a year, that's because they know that 2 units is 2 units after that long, but it's variable enough that you're not going to just get rid of something so expensive and precious when it's likely to still work just as well, and even if it's not "just as well," still be reasonably effective. It's a slow, steady decline, not a "this goes from fully potent to useless at this moment in time" kind of thing. Yeah maybe you'll give yourself four units and it'll actually be effectively 3.5; that's still better than zero.

The process of flocculation itself is autocatalytic and therefore ~exponential. Though the k factor might be low enough and minor deviations in the exact mechanism that are formulation-dependent might to make it look quasi-linear for quite a long time, followed by a precipitous drop.

Luckily during her last pregnancy my wife was prescribed substantially more insulin than she'd previously need for a month because the pregnancy was messing up her blood sugar, it stopped once she had the baby, but we still have the same dosage right now, so we are accumulating a small amount. That being said, it was the only way we could figure out to do it.