I keep going round in circles about the insulin cases.
My first point is always if there were concerns about the babies unstable conditions due to high readings etc, why wasn't more investigation done at the time? Why did it only come to light much later that a lab result was concerning, which could have given the opportunity to retest / try different treatments?
The fact that this, which I think is a failure in duty of care, and which in and of itself requires redress at hospital level, then became a lynchpin of the prosecution case, despite no physical evidence or eyewitness testimony, really bothers me. As does the less than robust defence.
Essentially it did boil down to Lucy Letby had access to the bags, therefore it's a certainty.
That's before you even ask "how much insulin, over how long, would produce the observed result in each baby, factoring in all the variables such as stickiness etc" and "can you show that amount of insulin was missing / unaccounted for from the unit"?
Whether or not it "must have been exogenous insulin from some source", I don't understand how it could be stated as incontrovertible fact without much more supporting evidence, with regard to the TPN bags.
The logic has obviously been that one hit via injection would have produced different observable results, so it must have been administered over a long period of time. However, the changing of the bags is a big spanner in the works.
One hypothesis I've seen is that the babies might have kicked in with immature systems "coming on line" - to do with glycogen stores etc.
And the big question is what was the point of all this in terms of motive for Lucy Letby? It's a very ham-fisted and uncertain method of achieving anything, as both babies survived. And the argument that it didn't work the first time, so she tried again holds little water. She must have known that at any point a test result would have sounded alarm bells.
It always puts me in mind of that US case of alleged FII where a mother was jailed for poisoning her baby with antifreeze. While in jail, without access to antifreeze, she delivered another baby who suffered the same symptoms. Turned out it was a rare syndrome that gave results mimicking antifreeze poisoning.
Which is why I get very picky about medical evidence used to put people in prison / remove their children.