In a very general sense, we think about glucose and sugar, when the issue is that our hormone that controls it, insulin, is out of balance.
Out of balance is a horribly vague term, but to keep it simple, if you imagine driving straight down the road, being out of balance is like only being able to make wild movements with the steering wheel - you veer off to one side, then correct and veer off to the other.
How to change that depends on the answer to
@Rachox - what you were eating, and what your general state is (again being vague, but almost everything affects this - not just diet, but general wellness, stress, sleep etc) - what is "normal" for you.
It is difficult - because you are seeing the end response (blood glucose level) of an incredibly complex machine - your entire metabolic and nervous system) and trying to figure out what is causing it.
Having said that - I totally believe that CGMs are amazing and the only way of giving you real insight into your own body.
What confuses some is the low after the high - but this is quite normal - it's the crash after the rush. Normal, but of course not what you want, and can make you feel really rough. The smoother you can make things - the better, and the CGM can give you clues as to how to do that for you...