If you have high blood sugar levels before going to sleep, the high blood sugar level may persist until the morning. A large dinner or a snack at bedtime can cause high blood sugar levels that last all night, as can too low a dose of insulin with dinner. Adjusting your medication or what you eat and when you eat may help. To keep your blood sugar stable throughout the night, eat a dinner that is high in protein, healthy fats and fiber, and with a moderate content of complex carbohydrates.
The sunrise phenomenon, also called the sunrise effect, is the term used to describe an abnormal increase in blood sugar (glucose) first thing in the morning, usually between 2 a.m. These causes of high blood sugar levels in the morning are the result of body changes and reactions that occur while you sleep. If you're low during that time, you may experience a blood sugar spike later on; this is usually associated with an overcorrection of the low level. The most important thing you can do to stabilize your blood sugar is to check your glucose levels at bedtime, during the night, and when you wake up to look for patterns.
The best-known reasons why blood sugar may be high in the morning include high-carbohydrate snacks for sleeping and a lack of diabetes medications. For more tips on how to stabilize glucose levels overnight, read “The Overnight Blood Sugar Conundrum” by Adam Brown. First, it's important to understand that certain hormonal changes that occur overnight can cause high blood sugar levels (hyperglycemia). If the blood sugar level is normal during this period, the sunrise phenomenon is more likely to be the cause.
If your doctor has prescribed a blood sugar medication, be sure to follow the dosage and schedule recommendations. For example, eating high-carbohydrate foods or eating candy before bed can cause high blood sugar levels in the morning. Maintaining healthy blood sugar levels during the day is a good way to prevent high blood sugar levels at night. If you need to readjust your glucose level before going to sleep, take enough glucose to stabilize your blood sugar.
Exercise and weight loss, if needed, are some of the best ways to increase blood sugar control in people with prediabetes. A related problem is known as the sunrise phenomenon, which occurs when you wake up with high blood sugar in the morning. If you continue to have high blood sugar levels in the morning after making these changes, see your doctor for advice.