If I recall correctly the law for BG when driving a car is that someone must not drive when unsafe and they will be dreamed to have taken reasonable care if they keep to the BG levels DVLA have defined. Eg the police can't look at someone meter to see if they have driven a car at the wrong levels unless the police have a reason to think they have driven dangerously. Likewise their is no way for the police to know if someone has eaten carbs when between 4 and 5.
How soon will the DVLA advice be updated to say that 4.5 with BG increasing fast is very different from 4.5 with BG decreasing.....
How does someone with a well controlled lopping system even know if they have hypo awareness?