Proper diabetes control means maintaining your blood glucose levels within an individual range that has been determined by a patients healthcare professional.
Before and after meals: This is when you should definitely check your blood glucose levels and how often it is necessary for you to check yourself on average.
You cannot dose your insulin correctly unless you know your current blood glucose level. The most important tips for measuring your blood glucose levels correctly.
Is your measured blood glucose value out of step with the way you feel? Why is that? Did an error occur with your test strip, your meter or during measurement?
Whole blood vs. plasma
If you switch from a blood glucose meter calibrated for whole blood to a meter calibrated for plasma or vice-versa, then you may need to adjust your target values.