Somogyi Effect Vs Dawn Phenomenon: Differences Worth Knowing

Have you ever gone to sleep with a relatively normal glucose reading and woke up with a much higher value? If Yes! Then you must be wondering why glucose numbers swing during sleep or during pre-dawn hours? Well! In the current article we will talk about the two possibilities namely the Somogyi Effect and The Dawn phenomenon.

We will know about the differences between the two possibilities in the following sections.

Somogyi Effect Vs Dawn Phenomenon

Somogyi Effect Vs Dawn Phenomenon: Differences Worth Knowing

Before we talk about the differences between Somogyi Effect and the Dawn Phenomenon, we would mention that both these phenomenon can raise your fasting blood glucose levels during the morning hours, but for different reasons.

Somogyi Effect Vs Dawn Phenomenon: Basic Differences

Somogyi Effect is also known as “Rebound Hyperglycemia”. The Somogyi Effect is a pattern of undetected hypoglycaemia or low blood glucose values of less than 70, followed by hyperglycemia or high blood glucose levels of more than 200. This effect generally happens in the middle of the night, though it can also occur when too much insulin is circulating in the system. During hypoglycaemia period, the body releases hormones which cause a chain reaction to release the stored glucose. The end result is that the level of glucose can swing extremely high in the other direction, causing hyperglycemia.

The Dawn effect is named after the time of the day it occurs. This phenomenon is the body’s response to hormones released in the early morning hours. Such an effect occurs for everyone. When we sleep, hormones are released in order to help maintain and restore cells within our bodies. These counter-regulatory hormones like growth hormones, catecholamines, and cortisol cause the rise in glucose level. There is a high glucose reading in the morning for those people with diabetes who do not have enough circulating insulin for keeping this increase of glucose under control that occurs due to the counter regulatory hormones. The dawn phenomenon is even more exaggerated because of additional hormones released in the night.

Somogyi Effect Vs Dawn Phenomenon: Differences Based on the Causes

The somogyi effect is caused by having excess of insulin in the blood during the night. This can occur in people who take long-acting insulin or in case of people who are required to eat a snack before bed for keeping their blood sugars stable. This is because there is enough insulin in the blood but not enough glucose, which cause the blood sugar to drop while the individuals are sleeping. In response to this, the body releases hormones to counteract the drop in glucose levels. This is the reason why in the morning the person wakes up with higher blood glucose levels.

In case of the dawn phenomenon, it is not caused by low blood sugar, but caused by a surge of hormones that the body puts out in the early morning hours. At this time, the body makes less insulin and hormones trigger the liver to put out more of glucose. Without enough of insulin to counteract this, there is a rise in blood sugar which is why the blood sugar level is very high in the morning. It must be noted that everyone has the dawn phenomenon, if you have or do not have diabetes.

Somogyi Effect Vs Dawn Phenomenon: Differences Based on Test Results to know Which One Could be Causing High Morning Glucose Levels

The only way to test if it is the Somogyi Effect or the Dawn Phenomenon that is making your morning glucose levels high is to wake up sometime in between 2 and 3 AM for several nights in a row and check your blood sugar reading. In case you have low blood sugar at that time, it could be the Somogyi effect. However, in case you are normal or high blood sugar level at that time, it is the dawn phenomenon which may be the culprit.

Somogyi Effect Vs Dawn Phenomenon: Differences Based on How to Counteract the Two Effects

Some of the best ways to counteract Somogyi effect includes the following:

Make a check that you are having a snack before bed and the snack consists of more protein than carbohydrates. You can take a piece of toast along with peanut butter, yogurt, some nuts, small pieces of cheese etc.

Let you doctor know what is happening with you. He or she may change your medication or dosages of insulin.

Do not skip or change your medications without your doctor’s input.

Some of the best ways to counteract the Dawn Phenomenon includes the following:

  • Have your dinner earlier in the evening. Make sure you avoid taking carbohydrate late at night.
  • Exercise in the evening which may help keep morning blood sugars in a better range
  • Talk to your doctor about everything happening. You may require adjusting the time of taking medication or type of medication.
  • Eat breakfast in order to limit the effect of Dawn phenomenon. By eating breakfast, your body will signal the counter-regulatory hormones to turn off.


We now know about some of the differences between the Somogyi Effect and the Dawn Phenomenon. Irrespective of how we label high glucose values, i.e. whether caused by the Somogyi effect or the Dawn Phenomenon; we must try to figure out their cause and take necessary steps accordingly for managing the diabetes or the blood sugar levels in the body.

Kindly consult your doctor for the best advices and do not change or stop your prescribed medications without consulting your doctor.

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:February 2, 2018

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