What's the importance of recording my fasting and postprandial blood glucose results?

Glucose monitoring. The whole purpose of monitoring your blood sugar levels is to let the doctor know what they are running so that the doctor can adjust your medications. Having good blood sugar control is essential in preventing complications. If the doctor isn't getting those values then i would wonder why you're checking it also. Bring in the averages or ranges of blood sugars when you see your doc.