Dawn Phenomenon (Liver Dump)

Dawn phenomenon is the term given to an increase in blood sugar in the morning caused by the body’s release of certain hormones.

It is a relatively common phenomenon amongst diabetics

Although often confused, Dawn Phenomenon is different from Chronic Somogyi Rebound , because it is not brought on by nocturnal hypoglycemia.

How is dawn phenomenon caused?

Dawn effect occurs when hormones (including cortisol, glucagon, epinephrine) are released by the body, causing the liver to release glucose.

The dawn effect therefore describes abnormally high early morning increases in blood glucose :

  • Usually abnormally high blood glucose levels occur between 8 and 10 hours after going to sleep for people with diabetes

Why does the dawn phenomenon occur?

Researchers think that the release of the above-mentioned hormones may give rise to a brief period of insulin resistance which would also explain a rise in blood glucose levels.


The dawn phenomenon is occurs when the body produces hormones that result in raised blood sugars in the morning.

It is thought that the body releases hormones that either impair the action of insulin or cause the liver to release extra sugar into the blood. This rise in blood glucose typically occurs around the time of waking.

Dawn phenomenon seems to affect some people but not others. There are theories as to why some people may be affected and not others but it’s not yet so well understood.

If you have high blood sugar it may or may not be a result of dawn phenomenon. If you are puzzled as to why you have high blood sugars in the morning, you may wish to wake and do a blood test in the night.

If your level during the night is significantly lower than your waking blood test result, then dawn phenomenon is likely.

People on an insulin pump may be able to take measures to avoid dawn phenomenon from pushing your sugar levels higher. Reduction of carbohydrate intake, particularly for evening meal may help to reduce the effect of dawn phenomenon.

Increased medication dosage may help but consult your doctor as hypoglycemia may result from overdosage.

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How is dawn phenomenon treated?

Typically dawn phenomenon is treated by avoiding intake of carbohydrates at bedtime, adjusting how much insulin or medication is administered, switching to other medications or using an insulin pump.

I have high morning blood sugar, do I have dawn phenomenon?

High morning blood sugar can be down to a variety of things, including insufficient insulin, incorrect medication dosage, carbohydrate snacks before bed and more.

Testing blood glucose during the course of the night (say between 2 and 4 am) may help to establish when blood glucose levels are rising and therefore whether you are experiencing dawn phenomenon.

How do I correct dawn phenomenon?

Your doctor or healthcare professional will be able to help you to correct either dawn phenomenon or alternative reasons for high blood glucose levels in the early morning.

They may suggest one of the following to help stabilise your morning blood sugar levels:

  • Adjusting insulin dosage
  • Adjusting medication dosage
  • Switching to different medication
  • Switching to an insulin with a different profile of activity
  • Not eating carbohydrate snacks before bed
  • Using an insulin pump to administer extra insulin
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