That is pretty confusing, and I totally understand the sense of... "if I don't understand what's going on, what's the point of trying..."
My sense.. (and I'm not a doctor.. so take this for what it's worth...) is that while we think about controlling blood glucose, because that's what we can measure.. it's all more a question of being out of balance hormonally.. high blood sugar indicates likely high blood insulin, and repeated high insulin will give rise to insulin resistance, which can affect everything. Psoriasis and Pneumonia are both inflammatory conditions which have direct links to insulin resistance.. and if you turn it over in your head... lifestyle leads to insulin resistance leads to outcomes which can be inflammatory and higher blood glucose over time...
In other words .. through this period, I think I would see it that you have just had other outcomes.. you have gotten past that (I think, from what you've said) and now from a better heath baseline, you can look to the next period.. and gather that motivation.
Ie, it's all connected. The best part if this is that over time, if you can bring down your level of insulin resistance, you may find that you also have health benefits across the board..
I hope this helps (I realise it's complicated..) but to me, you don't need to think that "these things happened, and independently, my BG went down when I expected it to go up" .. they are all connected, and anything you do to control your BG will help your insulin levels, and that will help the other inflammatory conditions too..