Diabetes and Low Blood Sugar in the Morning - An Overview

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Diabetes and Low Blood Sugar in the Morning

Diabetes is a disease that results in blood glucose values that are higher than normal. The challenge of type 1 and type 2 diabetes is to maintain a near-normal blood glucose average, called an A1C. This can be difficult, and people who strive for good control of their diabetes often walk a fine line between normal blood sugar and low blood sugar.

What is Low Blood Sugar?

Low blood sugar is usually defined as a blood glucose value below 72 mg/dL. Meters have the potential for error, so it is important to take this into account when gauging whether your blood sugar is low. A blood sugar value that is just a little bit above the low threshold may actually be low.

What Are the Symptoms of Low Blood Sugar?

The symptoms of low blood sugar include endocrine responses such as an elevated heart rate, sweating, shaking and confusion. Over time, people with type 1 and type 2 diabetes who are on medication may experience so many low blood sugar events that they no longer have any symptoms. This can be dangerous, because severe low blood sugar can lead to unconsciousness.

Normal Morning Blood Sugar Values

People who do not have diabetes may have slightly low blood sugar in the morning. They may experience blood sugar values under 72 mg/dL. However, in people who are on pills or insulin, blood sugar is managed artificially, so there is more of a chance for it to go significantly below 72 mg/dL. This can be dangerous if it is not treated properly.

Changes in Medication Regimes Can Cause Morning Low Blood Sugar

People with type 1 diabetes rely on insulin to survive, because they have a pancreas that no longer works. Many people with type 2 diabetes use pills or insulin to manage their blood sugar. These medications are engineered to bring the blood sugar down slowly over the course of the day and night. Insulin regimes and medication doses vary significantly from person to person, depending on body size, insulin resistance, recent exercise, stress and illness, hormones and many other factors.

Regular Blood Sugar Testing and Snacks Are Important

People with diabetes who are on medication need to make sure they have regular, scheduled meals and snacks to ensure that they do not experience low blood sugar. This includes a bedtime snack. If someone who is on pills or insulin injections forgets the bedtime snack, this can lead to low night time and low morning blood sugar.

Other Causes of Low Blood Sugar in the Morning

If you have exercised a lot the day before or have recently lost some weight, your insulin resistance will usually decrease. This means that you may experience low blood sugar values overnight or in the morning if you continue to take your regular dose of insulin or pills. If this occurs on a regular basis, contact your doctor about changing your dosage.

Low blood sugar in the morning can also occur as the time of sunrise changes during the year. Many people experience something called the Dawn Phenomenon, an increase in the blood sugar values just before dawn. If you head to the lab to test your fasting blood sugar at 9 am, the sun is likely up already and you may have a higher fasting blood sugar. Your doctor will try to reduce this fasting blood sugar value by giving you pills or insulin to reduce the number. However, it is equally important to make sure that this dosage does not make you experience low blood sugar in the night or the early morning before dawn. If you find that you awaken early with a low blood sugar and do so often, check with your doctor about changing your dosage. You can also add a bedtime snack of fat, protein and carbohydrates to elevate your blood glucose slightly during the night.


American Diabetes Association. The Dawn Phenomenon. https://docnews.diabetesjournals.org/content/3/7/5.full

Lana M. Bell, Katie Watts, Aris Siafarikas, Alisha Thompson, Nirubasini Ratnam, Max Bulsara, Judith Finn, Gerry O’Driscoll, Daniel J. Green, Timothy W. Jones and Elizabeth A. Davis. 2007. Exercise Alone Reduces Insulin Resistance in Obese Children Independently of Changes in Body Composition. The Journal of Clinical Endocrinology & Metabolism Vol. 92, No. 11 4230-4235. https://jcem.endojournals.org/cgi/content/abstract/92/11/4230

National Diabetes Information Clearinghouse. Insulin Resistance and Pre-Diabetes. https://diabetes.niddk.nih.gov/dm/pubs/insulinresistance/