Whilst I know if I eat very late, there is a change my fasting level will be elevated, it's not usually significant. I would say a more significant factor for me in what I eat, when I eat later. Lots of protein takes longer to reduce.
In a recent 24 hour, hourly testing experiment, I found that late evening, through the night to early morning, my bloods moved a round a bit. I had a couple of lows in the night, then slight rises. To be fair though, my graphs have very, very few material spikes. My OH often remarks they look extremely boring. I take great reassurance from that!
I'm going to repeat the overnight testing some time before Mr B comes back to UK, to minimise on the silent (or not so silent) grumpiness in the night time.
I'd love a CGM, and am waiting for the new Abbott solution to appear with interest. If it was viable to "invest" for a period of close monitoring, I might just bite the bullet.
Are your current findings differing from what you experienced last time you started low-carbing?