Our morning readings are always the last to behave because there are so many factors that affect it, most of which are outside our control.
Have you read about the Dawn Phenomenon? This is when the liver dumps glucose in our system to help us start the new day when our tummies are empty. It is a natural event and happens to most people, non diabetics as well. Not much you can do about it. If you go to bed on a much lower number, you can bet it is either the DP or s bad restless night or stress. Keep clear of carbs at bedtime though. Have some cheese, a yogurt, or a couple of nuts, but not bread. I never have supper and I don't generally get a rise over night, but that's just me.