Why Is Blood Sugar High in the Morning?

Q. Why does my blood sugar go up in the morning when I've eaten right and taken my medicines?

A. You don't mention how high your blood glucose levels are rising. But blood glucose will increase after eating, even if you "eat right."

The main thing that affects fasting blood glucose is the amount of glucose that the liver releases during the night. In type 2 diabetes, the liver tends to release too much glucose during sleeping hours. The body cannot process all that glucose properly because there isn't enough insulin, and the body resists the action of the insulin that is present. Insulin resistance tends to be more of a factor in the morning. So morning blood glucose levels are often too high.

Some people with type 1 have high blood glucose levels in the early morning because of the dawn phenomenon, in which the release of hormones contributes to elevated levels. Or glucose levels may rebound from overnight episodes of hypoglycemia (low blood glucose).

Keep testing your blood glucose two hours after your first bite of breakfast and write down what you eat. Then share the results with your health-care provider so you can adjust medication or your meal plan.

Virginia Zamudio Lange, a member of Diabetic Living's editorial advisory board, is a founding partner of Alamo Diabetes Team, LLP in San Antonio.