The Dawn Phenomenon
The dawn phenomenon is a natural process that occurs at the end of a night’s sleep when your body releases hormones, such as cortisol, adrenalin and growth hormone, to prepare the body for awakening, among other tasks. These hormones have a counter-regulatory action on insulin, and they encourage the liver to secrete glucose, both of which can increase the level of blood glucose (sugar).
Thus, it is possible to wake up in the morning with an elevated blood glucose (sugar) level even though it was within target values when you went to bed on an empty stomach.
Your medication might need to be adjusted to correct this problem. If so, discuss this with your doctor.