Have you heard of the Dawn Phenomenon or liver dump? There are dozens of threads about it on the forums if you use the search box.
Briefly, our livers produce and then release glucose in to our blood stream when they think our glucose is a bit low. That doesn't mean to say we are a bit low - just lower than our bodies have been used to. This is because we need extra energy when we wake up so we can start the day. It also happens at other times of the day, plus during exercise etc. It is quite natural.
You can stop it in its tracks sometimes by having something fatty (no carbs) as soon as possible after getting up. Otherwise it is likely to stay higher than you want throughout the morning.