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So, insulin pumps linked to continuous glucose monitors (CGMs) do exist. For example, "Tandem Control-IQ" or "Minimed Smart Guard". These are known generally as

So, insulin pumps linked to continuous glucose monitors (CGMs) do exist. For example, "Tandem Control-IQ" or "Minimed Smart Guard". These are known generally as "Hybrid closed-loop" systems. They work very well and generally offer positive outcomes for most people with Type 1 diabetes. They are called "hybrid" because they do not try to correct for carbs that you eat ("bolus"), rather they only try to adjust background insulin levels ("basal") and do some "mopping up" if you mis-dose for carbs you eat. The main things holding them back are that: - CGMs only measure glucose in interstitial fluid, which has a time-delay of 5-15 minutes from veinous blood glucose - Injected insulin also takes roughly 5-15 minutes to start acting and peak action is after an hour. That means your PID controller could have up to a 30 minute lag time to the system it's controlling. And let me tell you, blood glucose isn't a slow system. It can go from dangerously high to dangerously low in 30 minutes (or vice-versa). The body has the advantage that its insulin is faster acting, it can sense blood glucose changes faster, and it can use other sensors (e.g. glucose receptors in the mouth can start insulin production before it ever hits the bloodstream).

bayesian_horse 4y ago
"Artificial Pancreas" schemes usually use ultra-short-acting insulins which are even quicker acting than "regular human" insulin. There is virtually no immediate danger from high BGL (but medium to long term for sure!). High BGL over long time in Type-2 diabetes means there is actually too much insulin production for your own good, leading to high insulin resistance, leading to a situation where the cells aren't getting enough glucose at all. But this state takes some time to develop. Low BGL is the other way around: immediate danger, long term it's easier to buffer or control. Keep in mind those are generalizations. Don't take this as medical advice. Don't think I'm saying there is no need to react to high BGL.
- Benjamin_Dobell 4y ago
  > ultra-short-acting insulins which are even quicker acting than "regular human" insulin. Whilst this is true chemically, it's the delivery mechanism that causes the delay. The chemical composition of insulins like Novorapid (which my daughter uses) are slightly faster than regular human insulin, but not nearly enough to account for the aforementioned (up to) 30 minute lag.
  - user_7832 4y ago
    > The chemical composition of insulins like Novorapid (which my daughter uses) are slightly faster than regular human insulin Huh, thanks, I was not aware that novorapid is faster than endogenous insulin (most graphs show it much slower, albeit when taken subcutaneous). I switched from Novorapid to Fiasp because of how long Novo took to act, funnily enough. Also, moderate-fun fact: intramuscular injections, while a bit painful apparently, can release insulin much faster than subcutaneous. By much faster I mean Lantus/24hr insulin can make you hypo within an hour, as per what I read online on a particular post.
    - heisenzombie 4y ago
      I was told this by a GP who had Type 1 himself. I very occasionally do this with Novorapid into my shoulder muscle (one needs a longer than usual needle for this) to drop a high blood glucose fast, for example after a failed infusion site at night. It does feel weird, but it does work. (This is not medical advice! This is dangerous! Ask your doctor!)
- heisenzombie 4y ago
  Just as a heads-up, people with type 1 often bristle at people using their experiences with type 2 to talk about type 1. It’s incredibly common, but you should be aware (you actually might be!) that type 1 diabetes and type 2 diabetes are incredibly different diseases, having almost nothing to do with one another apart from that they’re related to blood glucose. Even insulin-dependent type 2 is a very different ballgame to type 1. I’m definitely not implying a ranking here or devaluing your experience with a serious chronic illness. Anyway, I’m thick skinned about this, so this isn’t really about me. I’m just trying to let you know that you could engender negative reactions by being unaware of this common “sore spot”. EDIT: Sorry, I see you’ve addressed this in a different comment, so you’re aware. All good, I’ll leave this up as general advice to others.

bayesian_horse 4y ago

"Artificial Pancreas" schemes usually use ultra-short-acting insulins which are even quicker acting than "regular human" insulin. There is virtually no immediate danger from high BGL (but medium to long term for sure!). High BGL over long time in Type-2 diabetes means there is actually too much insulin production for your own good, leading to high insulin resistance, leading to a situation where the cells aren't getting enough glucose at all. But this state takes some time to develop. Low BGL is the other way around: immediate danger, long term it's easier to buffer or control. Keep in mind those are generalizations. Don't take this as medical advice. Don't think I'm saying there is no need to react to high BGL.

Benjamin_Dobell 4y ago
> ultra-short-acting insulins which are even quicker acting than "regular human" insulin. Whilst this is true chemically, it's the delivery mechanism that causes the delay. The chemical composition of insulins like Novorapid (which my daughter uses) are slightly faster than regular human insulin, but not nearly enough to account for the aforementioned (up to) 30 minute lag.
- user_7832 4y ago
  > The chemical composition of insulins like Novorapid (which my daughter uses) are slightly faster than regular human insulin Huh, thanks, I was not aware that novorapid is faster than endogenous insulin (most graphs show it much slower, albeit when taken subcutaneous). I switched from Novorapid to Fiasp because of how long Novo took to act, funnily enough. Also, moderate-fun fact: intramuscular injections, while a bit painful apparently, can release insulin much faster than subcutaneous. By much faster I mean Lantus/24hr insulin can make you hypo within an hour, as per what I read online on a particular post.
  - heisenzombie 4y ago
    I was told this by a GP who had Type 1 himself. I very occasionally do this with Novorapid into my shoulder muscle (one needs a longer than usual needle for this) to drop a high blood glucose fast, for example after a failed infusion site at night. It does feel weird, but it does work. (This is not medical advice! This is dangerous! Ask your doctor!)
heisenzombie 4y ago
Just as a heads-up, people with type 1 often bristle at people using their experiences with type 2 to talk about type 1. It’s incredibly common, but you should be aware (you actually might be!) that type 1 diabetes and type 2 diabetes are incredibly different diseases, having almost nothing to do with one another apart from that they’re related to blood glucose. Even insulin-dependent type 2 is a very different ballgame to type 1. I’m definitely not implying a ranking here or devaluing your experience with a serious chronic illness. Anyway, I’m thick skinned about this, so this isn’t really about me. I’m just trying to let you know that you could engender negative reactions by being unaware of this common “sore spot”. EDIT: Sorry, I see you’ve addressed this in a different comment, so you’re aware. All good, I’ll leave this up as general advice to others.