Some poeple find that fasting in the morning can make their blood glucose keep on rising, or at least not falling.
Others find that fasting leads to numbers drifting downwards.
Your meter will quickly show which group you fall in.
If going without breakfast leads to higher numbers throughout the morning, then you can experiment to see what works best for you.
In my case, a protein and/or fat breakfast leads to a nice drop in readings. The mackerel mentioned above is good, likewise kippers would work for me. Also bacon and egg, or even just a cup of coffee with a dash of cream. Another option would just be a slice of cheese or ham, or both
I used to get +3 or 4mmol/l rising numbers if I fasted in the morning, which I learned to counter with a coffee with cream, or a proper breakfast.
Gradually, over 3 or 4 years low carb, then keto, then carnivore, my morning readings became less volatile, and now I am in the happy position of being able to fast all morning and
only see a rise of 1-1.5mmol/l by around 11am, which then drifts downwards til I eat.
However, I am delighted to report that a protein/fat breakfast will give me a 1-1.5mmol/l
drop - which is obviously a
much better short term result than if I fast completely.