1. One possible reason you ate much sugar rich food. 2. It was a short sleep. 3. If it is after a long night sleep than you are diabetic and MUST see a doctor NOW. 4. A healthy person should get up (after a long night sleep) with less than 110.
One explanation might be what is called the dawn phenomenon. See this article for more information. You need to talk to your doctor about this and he/she will discuss ways that you can prevent this from happening.
Because, as a diabetic, the balance of sugar (including insulin function) is damaged. Now, if you are talking night sleep, and you wake up with high blood sugar level, it is because of growth hormone released in the morning and raise blood sugar (to wake us up). As you are a diabetic, your body fails to turn the blood sugar back to normal again, thus you experience high levels.
Another explanation is because of insulin peak. If you are taking any medication, talk to your doctor to adjust the dose and time when to take that medication to not experience high or low blood sugar levels while nigh-sleep.
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