Why Is My Blood Sugar High in the Morning?

Medically Reviewed by Michael Dansinger, MD on December 08, 2021
2 min read

That early morning jump in your blood sugar? It's called the dawn phenomenon or the dawn effect. It usually happens between 2 and 8 a.m.

But why?

Generally, the normal hormonal changes your body makes in the morning will boost your blood sugar, whether you have diabetes or not. If you don't, your body just makes more insulin to balance everything out. You don't even notice that it's happening.

But if you have diabetes, it's different. Since your body doesn't respond to insulin the same as most, your fasting blood sugar reading can go up, even if you follow a strict diet.

The boost in sugar is your body's way of making sure you have enough energy to get up and start the day. If you have diabetes, your body may not have enough insulin to counteract these hormones. That disrupts the delicate balance that you work so hard to keep, and your sugar readings can be too high by morning.

The effects of the dawn phenomenon can vary from person to person, even from day to day.

Some researchers believe the natural overnight release of what are called counter-regulatory hormones -- like growth hormones, cortisol, glucagon and epinephrine -- makes your insulin resistance stronger. This will make your blood sugar go up.

You may also have high blood sugar in the morning because:

  • You didn't have enough insulin the night before.
  • You took too much or too little medicine.
  • You ate the wrong snack before bedtime.

If the dawn phenomenon affects you, try to:

  • Eat dinner earlier in the evening.
  • Do something active after dinner, like going for a walk.
  • Check with your health care provider about the medicine you’re taking.
  • Eat breakfast. It helps bring your blood sugar back to normal, which tells your body that it's time to rein in the anti-insulin hormones.
  • Eat a snack with some carbohydrates and protein before bed.

You'll also want to avoid all sugar-sweetened beverages, like soda, fruit punch, fruit drinks, and sweet tea. Just a single serving can raise your blood sugar -- and, in some cases, give you hundreds of extra calories.

If you have diabetes, chances are your blood sugar will be higher in the morning from time to time. That may not be something to be overly concerned about. If it happens for several mornings in a row, check it once during the night -- around 2 or 3 a.m. -- for a few nights. Then, take those numbers to your doctor. They can figure out if you really have the dawn phenomenon, or if something else is causing those higher morning numbers.

Show Sources

Diabetes Stops Here: "Why All the Morning Highs?"

Mayo Clinic: "What is the dawn phenomenon that some people with diabetes experience? Can anything be done about it?"

American Diabetes Association: "Diabetes Myths."

Diabetes Forecast: "Why Is My Blood Glucose So High in the Morning?"

diabetes.co.uk: "Glucagon."

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