Why your blood sugar is high in the morning and how to lower it

• Your blood sugar levels might be high in the morning if you are experiencing the dawn phenomenon or the Somogyi effect.
• The dawn phenomenon is most common in people with type 2 diabetes, while the Somogyi effect is more common for people with type 1 diabetes.
• To lower your morning blood sugars, you can try light exercise before bed, limit carbohydrates in the evening, and put more time in between your last meal and bedtime.
• This article was reviewed by Jason R. McKnight, MD, MS, a family-medicine physician and clinical assistant professor at Texas A&M College of Medicine.

People with diabetes have a more difficult time regulating their blood sugar. Those with type 1 diabetes are not able to produce insulin, the hormone that helps the body convert blood sugar into energy. And those with type 2 diabetes cannot use insulin effectively.

As a result, blood sugar levels are often much higher for people with diabetes, especially in the morning. Here's why.

What is the dawn phenomenon?

As your body prepares to wake for the day, it releases glucose stored in the liver to give you the energy you need to get going. However, people with diabetes are not able to utilize this blood sugar, so roughly half of diabetics experience high blood sugars in the morning. This is known as the dawn phenomenon.

If you have diabetes, your doctor will work with you to set a target range for your blood sugars. In general, blood sugar levels between 70 to 130 mg/dl are considered healthy for diabetes.

If your levels are consistently above your target in the morning, and you have not eaten yet, you might be experiencing dawn phenomenon. This is most common in people with type 2 diabetes.

Blood sugars typically peak about 2 to 3 hours before waking and can remain high as you wake up. For most people, that means the early morning hours, but if you have an abnormal sleep schedule you can experience this spike at any time.

"For individuals who work night shifts, the 'dawn' phenomenon may occur at dusk, since it's related to an individual's normal waking time, not the specific time of the day," says Joseph Barrera, MD, an endocrinologist with Mission Hospital in Orange County, California.

What is the Somogyi effect?

The Somogyi effect is a second explanation for high blood sugars in the morning, and this occurs most often in people with type 1 diabetes. It happens when people experience hypoglycemia — or low blood sugar — during the night. In an attempt to correct that, the body releases more stored glucose, which can then lead to high blood sugars in the morning.

The Somogyi effect is more rare than the dawn phenomenon, but that's mostly because fewer people have type 1 diabetes than type 2 diabetes. When a 2015 study published in Diabetology & Metabolic Syndrome followed 85 people with type 1 diabetes, it found that 82.4% of them had high blood sugars in the morning, and 60% of those were caused by the Somogyi effect, compared with just 12.9% caused by the dawn phenomenon.

To determine if your high blood sugars in the morning are caused by the Somogyi effect, Barrera says you'll need to see your blood sugar levels about 4 to 5 hours before you wake up, which can be done with a continuous glucose monitor.

How to lower morning blood sugar

You should talk to your doctor if you regularly experience high blood sugars in the morning, Barrera says. Your team will make recommendations on changing your treatment regimen that might help you avoid this morning hyperglycemia.

"High blood sugars in the morning can generally be addressed by careful attention to a diet and exercise regimen, and adjustments in diabetic medication by a qualified health professional," Barrera says.

To avoid dawn phenomenon, your doctor might tell you to take these steps:

• Avoid or limit carbohydrates in the evening
• Incorporate exercise before bed, like an after dinner walk
• Put more time between your last meal and bedtime

People who continue to have trouble with the dawn phenomenon might be advised to take insulin before bed, Barrera says. However, this has to be done carefully, so that it doesn't cause the Somogyi effect.

Takeaways

People who experience the dawn phenomenon often find that it gets worse over time. In fact, it's considered an indicator that diabetes is progressing, so it's important to talk to your doctor about treating it.

On the flip side, making the necessary changes to regulate the dawn phenomenon can lower blood sugar over time. In fact, research has found that it can result in a 0.5% decrease in A1C levels — a long-term measure of blood sugar — which can reduce your risk for health complications from diabetes.

Related stories from Health Reference:

• 5 of the best foods to lower blood sugar and manage diabetes
• How to lower your blood sugar quickly and what to do if it's an emergency
• Is diabetes genetic? Both Type 1 and Type 2 are influenced by family history — here's how to know your risk
• 5 ways to lower A1C and manage your blood-sugar levels
• Why it's so important for people with diabetes to limit their carb intake