Dawn Phenomenon
Does this ever happen to you: When you go to bed, your blood glucose reading is 110, but when you wake up in the morning, it has shot up to 150?
To understand how blood glucose can rise overnight without your eating anything, we have to look at where sugar comes from and where it goes while we are fast asleep.
During the day, the carbohydrates we eat are digested into sugar and absorbed into the bloodstream. Some of this sugar goes to the liver, where it is stored for later use.
At night, while we are asleep, the liver releases sugar into the bloodstream. The liver acts as our sugar warehouse and keeps us supplied until we eat breakfast. The amount of sugar being used is matched by the amount of sugar being released by the liver, so blood glucose levels remain constant.
So What Is the "Dawn Phenomenon?"
A rising blood glucose level between approximately 3 am and the time you wake up is called the "dawn phenomenon."
This is how it works: The liver is supposed to release just enough sugar to replace what is being used, and insulin works as the messenger to tell the liver how much is enough. But, if there's not enough insulin (as in type 1 diabetes), or if there's enough insulin but it cannot communicate its messages to the liver (as in type 2 diabetes), the liver starts to release sugar much too fast.
The result? Blood glucose levels rise. This is why blood glucose levels can go up between the time we go to bed and the time we wake up, even though we haven't eaten a thing since supper.
So what can you do about it? There are changes you may be able to make in the timing of your meals, medications or insulin injections to help prevent dawn phenomenon from occurring. First, keep a detailed record of what's happening at night and in the morning: your blood glucose levels, eating habits, medications or insulin and physical activity. Then, talk to your doctor or diabetes educator about changes you could make to prevent dawn phenomenon.