Why is my sugar high in the morning? - Doctablet®

Why is my sugar high in the morning?

Checking Blood Sugar, Doctablet Diabetes

It can be very frustrating to check your blood sugar and find it is always high in the morning. Diabetes is a complicated condition. There are many different factors that contribute to worsening blood sugars, including diet, hormones, exercise and genetics. A high blood sugar in the early morning can be caused by several things. The common ones will be covered below.


Causes of high blood sugar in the morning:

Insulin resistance in the liver:

The two main hormones involved in blood sugar control and regulation are Insulin and Glucagon. Insulin pushes sugar into the cell, so it can be used or stored. Glucagon does the opposite of insulin. It frees sugar from storage in the liver, so the body can use it while you are fasting.

A high blood sugar in the morning is one of the earliest changes people with diabetes experience. This is due to insulin resistance in the liver and high glucagon levels, which often occur in people with diabetes. The insulin the pancreas produces does not work well anymore, even though the pancreas is working overtime to produce more of it. Insulin resistance in the liver and elevated glucagon levels causes the liver to spill out extra sugar into the bloodstream while you are sleeping and fasting overnight. This raises your blood sugar levels.

The Dawn Phenomenon:

In the early morning, it is normal to have higher levels of cortisol  and growth hormone. Both of these hormones help prepare you to wake up and start the day. Doctors often call this hormone increase the ‘Dawn phenomenon.’ Dawn phenomenon happens between 2 AM and 8 AM, and it also occurs in patients without diabetes. This natural hormone change helps to keep sugar in the blood while a person is fasting. In patients with diabetes, the Dawn phenomenon is more noticeable because of both insulin resistance and decreased levels of insulin.

Both Dawn and Somogyi affect morning blood sugar
High blood sugar the night before

A high blood sugar in the morning can often be from high blood sugars left over from the night before. If the pancreas cannot secrete enough insulin after a large dinner or snack, you can have high blood sugars during the night and into the following morning. Many people with diabetes cannot recover to a normal blood sugar by the early morning, especially after a large carbohydrate filled meal.

The Somoygi Effect—a low blood sugar overnight:

Some medications for diabetes, such as insulin, can make your blood sugar go too low. When this happens, the body will rebound with stress hormones like glucagon and epinephrine that raise the blood sugar. This is called the Somoygi effect – named after the researcher who first described it.

Dawn phenomenon vs Somogyi Effect

Tricks to help lower your blood sugar in the early morning:

  • Skip the bedtime snack and limit carbohydrates (sugars, pasta, bread, rice) with dinner.

    Having a bigger lunch and a smaller dinner can often lower the morning blood sugar level. This is because there is less sugar available to the body overnight.

  • Try changing the time you take your prescribed medications.

    Metformin, the first-line medication for diabetes, is the best oral medication for reducing insulin resistance in the liver. Sometimes moving the evening metformin dose from suppertime to bedtime can help lower early morning glucose levels.

  • Exercise

    Exercise increases sugar uptake by the muscle. This increased sugar uptake lowers the amount of sugar in the blood for many hours after the activity. A safe exercise plan can greatly lower all of your blood sugars.

  • Stay hydrated

    Drinking plenty of water—not flavored or diet drinks—keeps you well hydrated. Sugar always travels with water, so it is important to keep up with the body’s need for fresh water to balance the blood sugar.

  • If you are on insulin, there might be a problem with your insulin dose.

    The first step is to find out if your blood sugar is running high or low in the middle of the night. If you have low blood sugars overnight, this needs to be corrected first in order to prevent the subsequent “rebound” effect.

How can I help my doctor figure out why my blood glucose is high in the AM?

Your doctor will likely recommend checking your blood sugar at bedtime and at 2 AM, in addition to the morning time. For patients on  complicated insulin regimens, a newer technology called continuous glucose monitoring might be used to trace the sugar levels over a longer period of time.

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Last Modified: Sep 17, 2018 @ 5:52 pm
About the Author

Chris Palmeiro D.O. M.Sc.


Dr. Palmeiro is Chairman of Endocrinology at the HealthAlliance of the Hudson Valley, he also serves patients with intellectual and developmental disabilities at the Westchester Institute of Human Development in Valhalla, New York. He has a Masters of Science degree in clinical nutrition and is a diplomate of the American Board of Internal Medicine. His interests within the realm of endocrinology include nutrition support, obesity counseling and the progressive management of diabetes.

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