Opinion varies.
I like the targets that Jenny Ruhl explains in
www.bloodsugar101.com mainly because she looks at studies and discusses why - and the consequences if we don't hit those targets.
The post meal guidelines are subject to change, anyway. As are the HbA1c targets. Committee decisions on cost of treatment, and new research all affect them, whether for the better or worse.
I personally think that any reading outside non diabetic 'normal' blood glucose carries a risk. Jenny Ruhl explains all that too, if you have a look.