It could be blood sugar related (high or low), it could be anxiety, it could be something else altogether. Two options here
1) go see your doctor and ask for suggestions
2) buy a blood glucose meter and test at night
I'd probably go for number 1 unless you've got some additional reasons to suspect a blood glucose disorder. There are too many possibilities for a non doctor to diagnose, or even suggest, a solution. If the doctor is no help and you still think it's blood sugar related you could go for option 2. Good luck.