Just to add that I have often when experimenting gone from normal blood glucose levels to mid teens mmols quite a lot.
This is because I was told to eat certain foods that was supposed to be healthy for me. Porridge, spuds, rice, any bread and because I'm lactose intolerant, any dairy.
Those foods were making me so ill and I didn't even know.
Having read the thread, I don't believe you have a form of Hypoglycaemia, but your metabolic condition definitely need investigating.