Do you not test on waking (fasting test)? I don't see any value in testing after I've been up for a while, especially if I've eaten.
I'm a slow starter in the morning so I've been testing after getting out of bed, p, feeding the cats and a weigh-in, so around 20 minutes after getting out of bed. I can't face that much co-ordination before all that - especially as hands are covered in barrier cream and contaminants. I was getting rogue readings before I figured that out.