The perfect time to check the fasting glucose levels is right after your wakeup. And the right time to check postprandial (post-meal) glucose levels is two hours after you have your meals.
A gap of two hours after a meal must be maintained to get the correct reading.
This helps you choose the right foods and medication. When you test before your meal, it tells you how much medication you need and when you test two hours after eating, you know if your medicines are working fine for you.