For quite a while I have noticed that testing 2 hours (8+), after a meal my reading is still on the high side but after 4 hours it is back to around 6.4
Is this OK?
It would help if you told us what type of Diabetes you have and any treatment you’re on, but in the meantime take a look at this: https://www.diabetes.co.uk/diabetes_care/blood-sugar-level-ranges.html
As a type 2 I test pre meal and at 2 hours after first bite, a lot do but so long as you test consistently, normally between 90 mins and 2 hours post prandial is acceptable. The closer your post meal reading is to pre meal the better.