Dawn Phenomenon and Somogyi Effect

Background: A blood glucose level taken first thing in the morning before eating or drinking anything will tell you how well your basal, or background (long-acting) insulin is working.  In order to determine if the Dawn Phenomenon or the Somogyi effect is affecting morning levels, you should test glucose at 2-3 a.m., and depending on the result, your health care provider may decide to adjust the treatment. If you don’t use insulin, it will indicate how well your own body is doing with insulin production based on current oral medications.  If your fasting blood glucose level is running over your target blood glucose level for a few days in a row, your health care team may suggest an increase in your basal insulin, or a change in medications.  The key for analyzing any blood glucose Fvalue is to establish a pattern by charting your blood glucose readings.

What else is important to know about your fasting glucose tests?

Sometimes your blood sugar levels may rise. If you can identify the reason, the solution is simple. However, there could be some days in which you wake up with high glucose levels for which you have no explanation. Let’s explore some of the reasons why we might have high fasting sugar levels in the morning and how they can be addressed.

There are two known symptoms of diabetes that may cause high fasting glucose.

The Somogyi effect and the Dawn Phenomenon both cause higher blood sugar levels in the morning. The dawn phenomenon happens naturally, but the Somogyi effect usually happens because of problems with your diabetes management routine.

Dawn Phenomenon is a normal body response which results in a rise of blood sugar in the early hours of the morning to produce energy for the coming day (this usually happens between 3 a.m. and 8 a.m.). The natural overnight release of regulatory hormones including growth hormone, cortisol, glucagon and epinephrine increases insulin resistance, causing blood sugar to rise. The liver stores fuel in the form of glucose, and while you sleep, hormones are released that signal the liver to release glucose to the blood stream. In a person without diabetes, the blood sugar levels would return to a balanced state. But for a person with diabetes, the resulting rush of glucose into the bloodstream causes hyperglycemia (high blood sugar) that remains high because there is not enough insulin available to counteract this effect.

Somogyi effect is the result of low sugar in the middle of the night – hypoglycemia. This could be a result of incompatibility in the dose of medications or insulin. Because of this low blood sugar, the body responds by releasing hormones such as glucagon and epinephrine that cause the liver to release glucose in order to overcome the hypoglycemia. The result of this liver reaction to night hypoglycemia is reflected in the fasting glucose test. This pattern of undetected hypoglycemia followed by hyperglycemia is called the Somogyi effect, also called rebound hyperglycemia.

How do we treat these two phenomena?

Never assume that you can fix this imbalance with extra medication or insulin or skipping breakfast; that would be a risky assumption. In order to determine Dawn Phenomenon, or the Somogyi effect you should test glucose at 2-3 a.m. at night, and depending on the result, your health care provider may decide to. adjust the treatment.

In case of very low reading (hypoglycemia) it is likely you may experience Somogyi effect and you will need to re-check your medicine or insulin dosage with your healthcare provider.

In case of very high number (hyperglycemia) you may be experiencing the dawn phenomenon and you will need to consult with your healthcare provider to discuss further options of insulin and medication dosage and timing or avoiding carbohydrates at bedtime.

Don’t forget to consider and share with your health care provider other factors that can affect your glucose increase like change in medications, illness, eating habits, exercise, work schedule.