Hi and welcome aboard,
Diabetes is a very confusing, and very mysterious disease. What needs to be remembered is that carbohydrate causes blood sugars to rise, and not only that but so does stress, illness, injury, disturbed sleep, other medications, and the state of our hormones. Having just been in hospital myself I can testify that unless you have your own food brought in for you, it is virtually impossible not to eat carbs. Add to this the stress and everything else you may be experiencing whilst in hospital, and it is no wonder your levels have increased.
However, 23.6mmol/l is very high. What were you doing in that period when they increased so much?
I also found that the blood sugars were taken randomly with no regard to timing after or before meals, and no chance to wash my hands before being finger pricked, so to me were a waste of time. I had my own meter with me and kept tabs that way. I should add that I am T2 and not on any diabetes medication.