What is the dawn phenomenon?    

The dawn phenomenon is an early morning rise in blood glucose levels.  It is due to a night time increase in certain hormones, which provides energy to help you wake. 

How common is it?    

Studies show that around half of all people living with type 1 or type 2 diabetes experience it.  

How do you know you have it?    

The main sign is an elevated glucose level in the early morning usually between 4am and 8am.  You go to bed, your glucose level is 5mmol/L.  When you wake, it is above this. How much higher depends on the individual.  You may want to monitor between 2am and 6am, or on waking, to see if there is a rise.   

 Causes  

Stress hormones, such as cortisol, glucagon, and adrenaline, are released overnight and your liver releases glucose into the system in response to these hormones.  These hormones can also increase insulin resistance. Making it harder for insulin to do its job.  

• In a person without diabetes there is no rise in the morning. This is due to the body being able to produce more insulin to counter the effects of the stress hormones.    
• Those living with type 1 diabetes need to rely on previously injected insulin, which may not be enough. If not enough, it can lead to a rise in fasting blood glucose.   
• Those living with type 2 diabetes, may not be able to produce the right amount of insulin to regulate the overnight glucose release and/or their insulin cannot do its job effectively. This may also lead to a rise in fasting blood glucose.  

Why do something about it?

It is important to keep blood glucose in your individualised target range to prevent damage to blood vessels and nerves. This reduces your risks of diabetes-related complications.  The general fasting blood glucose target range, for those who have type1 or type 2 diabetes, is between 4 and 7mmol/L.  Do note your doctor may set your target at a different level. For more information see the NDSS blood glucose monitoring fact sheet.  

Treatment and prevention    

It takes effort to deal with elevated fasting glucose levels.  Reach out to your diabetes team to discuss some of the following options:   

• Reviewing your insulin – need, type, dose, and timing.  
• If you use an insulin pump, you can consider setting the insulin rates to vary overnight, giving more insulin when glucose is released. Another option is using a hybrid closed-loop insulin delivery system. This is where you wear a continuous glucose monitor which feeds glucose data to your insulin pump. The pump adjusts your night time background insulin rates automatically. It is an excellent way to keep your blood glucose in target range over night.  
• Adjusting oral medication, type, dosage, and timing.  
• Eating enough carbohydrate for your needs during daytime hours and avoiding snacking before bedtime.  
• Maintaining healthy fat levels in your body and reducing your insulin resistance.   
• Being physically active to increase insulin sensitivity.  
• Walking, or working out, after dinner may reduce your overnight and fasting glucose levels.   
• Exercising in the morning, to use up the extra glucose.   

For guidelines, see the NDSS Physical activity factsheet.

Remember when changing your activity levels, especially before bedtime, it is best to monitor your glucose levels. You could be at risk of having low glucose levels, known as hypoglycaemia (hypo).  Discuss how to prevent and treat hypoglycaemia with your diabetes care team.

 If you have any general questions around the dawn phenomenon or glucose levels, call the NDSS help line on 1800 637 700.  You can receive a call back and speak with a credentialled diabetes educator, accredited practicing dietitian or accredited exercise physiologist.   

  By Monica McDaniel-Wong, Credentialled Diabetes Educator