The PID mindset, maybe with a "bayesian" bend, is generally the right idea. You have to realize from the outset that you're not going to predict the results of your actions correctly, and you can't even tell afterwards what effect your particular actions had. Which is frightening. Internal medicine is a lot about "let's try this common dosage and see what happens". It gets worse with an organism still growing, which means the dosages and effects have a long-term trend at the least.
In my (non-human-medical) opinion, low blood sugar is on average better than high blood sugar, especially for patients who don't need to walk around unsupervised and operate heavy machinery (i.e. cats, dogs, small children). An adult Human body only has on the order of 3g of sugar circulating in its blood at any time. We can easily generate blood sugar from protein. It's much harder to eliminate high blood sugar. Even extreme overdoses of injected insulin often only result in a coma that the patients can often recover from on their own because they metabolize the insulin and generate the glucose. I'm not recommending that, of course!
Low blood sugar however, is an immediate problem, high blood sugar is a long-term problem. Getting the balance right is hard, especially for Type-1 Diabetes. In overweight Type-2 patients (like I was) usually the patient's liver is so good at generating glucose that it buffers a wider range of insulin dosages and you have more time finding the lowest sufficient dose. Insulin is bad for your health, it means too much glucose is deposited everywhere in your body, leading to all sorts of problems. But too much glucose in the blood is even worse, so...
Low BG is a nonstarter, because it immediately impairs you. You will crash your car. You will get confused and fight someone. You will pass out and not be able to reach glucose. That coma will cause brain damage.
And, if you have back to back hypo episodes, you will actually fry both your body's natural counterregulation (you deplete your glycogen store, which makes subsequent hypo events more severe) and your neurological response to hypo (you lose awareness that you are hypo). In the long term, after too many lows, you will lose your ability to recognize hypo entirely.
The brain/metabolism link runs deeep into the lizard brain. Real deep.
A non-diabetic with a 5.5% A1C is doing just fine. Someone with Type 1 with a 5.5% A1C is almost certainly critically endangering themselves and everyone on the road.
I agree with this but your numbers are off IMO. Diabetics who use closed loop systems diligently can achieve A1Cs nearer to 5 without becoming dangerously low all the time. It is hard, but new tech is making it easier. Also an A1C of 5.5 is at the very top of the acceptable range before being pre-diabetic (5.7). Lastly, your nervous system becomes accustomed to the blood glucose range that you are frequently in... there are studies about T2Ds with A1Cs of like 9 who get low blood sugar symptoms when their glucose is ~90mg/dl (normal). So A1C of 5.5 in T1D does not automatically imply dangerous hypos all the time, maybe A1C of 4.9 does though.
I did qualify "as long as you don't have to run around unsupervised and operate heavy machinery".
A BGL as low as to cause brain damage can only result from insulin overdose. And it must be quite a bit off, which means it is easier to avoid.
I also qualified everything with "on average". There are people, depending on habits and their particular circumstances/medical condition, who will have a harder time with the "rollercoaster" even compared to most type-1 diabetics. But that is what qualified diabetes assistents are supposed to help them with.
Also: I'm not a diabetic, but I studied veterinary medicine and know quite a bit about it also from a Human perspective.
Yes. Realistically, it is difficult to reach a bad end from a single, isolated hypo event.
But I have myself made the mistake of underestimating hypoglycemia. Growing up, I always had issues of under-dosing insulin, because my bodyweight was always increasing; it seemed like I could always get away with giving a bit more insulin. When I stopped growing in my early 20s, I kept on with the aggressive dosing (got frustrated with the high BG feeling!) and had a string of severe hypo incidents. I had no idea what was happening during these events, but not only that, my neurological response changed and I had hypoglycemic unawareness. And, since I was so aggressive with insulin, my counterregulation was gone, so doses and meals that used to end in 80mg/dL were now ending in 30 mg/dL. And because my neuro response changed after the first few, I would slip into complete unawareness even during a mild 55 or 60 mg/dL.
Unawareness feels like: gosh there is something going on but I don't know what. There's something that I urgently need right now (sugar), if only I could place it. I have to be somewhere (work) this morning, but I don't know where... Imagine having a vivid dream, in which something in the room (like a person talking next to you or a fan turning on or something) affects the dream. Now, while you're in the dream, try to figure out what and where that thing actually is. It can be very very difficult, because it's like, the bug is in the operating system.
You can easily die from this, and many people do, I think the common figure is 1 of 20 t1d end up dying this way. Overaggressive treatment after the honeymoon period ends, when growth stops, or when changing insulins (like moving from long-acting to the pump), or even just having a bad flu -- there are many ways to make this mistake. And it is not obvious at all when you are making this mistake.
It's somewhat common to hear from diabetics at my work that they slip into a diabetic coma regularly from this sort of thinking. It's rough, and definitely not better than a slightly high level.
In my (non-human-medical) opinion, low blood sugar is on average better than high blood sugar, especially for patients who don't need to walk around unsupervised and operate heavy machinery (i.e. cats, dogs, small children). An adult Human body only has on the order of 3g of sugar circulating in its blood at any time. We can easily generate blood sugar from protein. It's much harder to eliminate high blood sugar. Even extreme overdoses of injected insulin often only result in a coma that the patients can often recover from on their own because they metabolize the insulin and generate the glucose. I'm not recommending that, of course!
Low blood sugar however, is an immediate problem, high blood sugar is a long-term problem. Getting the balance right is hard, especially for Type-1 Diabetes. In overweight Type-2 patients (like I was) usually the patient's liver is so good at generating glucose that it buffers a wider range of insulin dosages and you have more time finding the lowest sufficient dose. Insulin is bad for your health, it means too much glucose is deposited everywhere in your body, leading to all sorts of problems. But too much glucose in the blood is even worse, so...