Welcome to the board, 1003hjf! Always happy to see new faces.
Your after-meal (post-prandial) glucose levels depend on what you ate . . . there are a few foods that are notorious for causing a delayed reaction like that - pizza being one of the frontrunners. And not just a delayed reaction, but sometimes a prolonged reaction too, meaning it takes longer to drop back to normal too. What did you have for dinner tonight?
Has your doctor firmly diagnosed you, or is he just having you monitor for now? Hope you'll settle in here & we can get better acquainted.