Dawn Phenomenon

Dawn Phenomenon

If you have ever woken up to find your blood sugar levels have taken a sunrise hike of their own, you’re not alone. This normal occurrence is called the dawn phenomenon. Let’s explore what it is, what causes it, and what you can do to help combat it.

What is the dawn phenomenon?

Dawn phenomenon, sometimes referred to as the dawn effect, is a noticeable spike in blood sugar levels in the morning, typically around dawn. It most commonly happens in people with diabetes, including both type 1 and type 2 diabetes.

The cause of dawn phenomenon

Although the cause of dawn phenomenon is not certain, it is believed to be linked to early morning hormone levels. Hormones like cortisol signal your liver to increase sugar (glucose) production. The body does this to give you energy and wake you up, but it also increases sugar levels in the blood. For people who don’t have diabetes, the pancreas responds appropriately and releases insulin to regulate sugar levels. However, for people living with diabetes, this spike in glucose production coupled with or without insulin resistance can cause higher levels than are expected. 

One way to identify dawn phenomenon is by wearing a continuous glucose monitoring (CGM) device. This can also help determine if it’s dawn phenomenon or Somogyi effect. Often confused with each other, the Somogyi effect is defined by morning high blood sugar that’s caused by overnight hypoglycemia. In these cases, the body compensates to correct the low, rather than just an increase.

Common symptoms

How can you tell if you are experiencing dawn phenomenon? You may have some, all, or none of these symptoms:

  • Increased thirst
  • Frequent urination
  • Increased hunger
  • Vision changes
  • Irritability
  • Headaches

It’s possible to not have symptoms, which is why a CGM or routine morning blood sugar tests are important.  

Managing dawn phenomenon

There are short- and long-term effects that can result from uncontrolled high blood sugar levels. Some of these include:

  • Higher A1C
  • Increased risk of heart disease
  • Diabetic neuropathy
  • Retinopathy

Reach out to your endocrinologist to determine the best strategy for management if you experience dawn phenomenon.

Insulin pumps can help

CGMs are helpful to see patterns of sugar levels in the morning and overnight, but a CGM alone is not enough. Your healthcare team may suggest insulin pump therapy. An insulin pump can automatically deliver insulin to bring sugar levels within an acceptable range. Insulin pump systems, like the MiniMed™ 780G system, combine a CGM and insulin pump to monitor your sugar levels all day and night. The MiniMed 780G system is designed with SmartGuard technology, an advanced algorithm that uses current and past sugar level trends to anticipate and adjust insulin needs as well as correct high sugar levels. This means that even if your levels are high due to dawn phenomenon, the system will automatically act to correct it.  


Dawn phenomenon can affect many people living with diabetes, but it is easy to identify with either regular blood sugar tests or CGM readings along with adjustments of medication and/or nutrition. Insulin pump systems, especially the MiniMed™ 780G system, can help combat the naturally occurring spikes during early morning hours, and even throughout the day. Be sure to discuss your symptoms, glucose trends, and options with your healthcare provider.   

Guest author: Medtronic employee - Lisa Nicolussi, RN BSN CDCES 



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Submitted by Gordon Wetherby Chew (not verified) on

In reply to by Commenter (not verified)

My 780 G can not regulate this dawn phenomenon so I lie to the pump and typically ask for 1+ unit(s).

Submitted by RUSSELL A SMITH (not verified) on

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Great information concerning the "Spike" we get in the morning. I also notice a slighter spike in the afternoon as diner time approaches. With the help of my CGM I am able to manage this quite well. Diabetes is a "Full Time Job" which we can manage if we stay in tune with our bodies. I have had Diabetes Type 1 since 1981 and I try to hold my own! My A1C is constant 5.9-6.0. I hope and pray that others with this horrible disease pay attention and "Do Your Best" to manage it!

Submitted by sabrina.hudasanchez on

In reply to by RUSSELL A SMITH (not verified)

Hi Russell, thank you for sharing. Happy to hear you're doing well managing!

Submitted by Thomas S Hobbs (not verified) on

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good afternoon, I read your article and got to thinking. I have that happen but it is usually 30 to 45 minutes after I wake-up. I'll be in range(80_130), and my BG will rise to 175_ 195 range, before I eat. it's not every day but it does happen 1 to 2 times a week. And yes my Endocrinologist does know. She knows it all.
thanks, I'll keep my eyes open for another article

Thank you for all the information it was so helpful. My name is Delia Kolander I have had Type 1 Diabetes for 50 years. I have been on an insulin pump for about 20 years. I know about the ups and downs that we have to go through. Thank’s to God and my Endocrinologist Dr Lourdes Concha.

Submitted by Norma Gomez (not verified) on

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Hello Sabrina, I have had type 1 diabetes for 36 years. I have been on an insulin pump since 2000 & on Medtronic for the last 5 years or so. I love being on a pump & I’m now on the 780 G system since 10/18/23. I’m still in the early stages of learning it. My concerns are more along the range of highs than lows. I can more easily deal with the low than a high(which I absolutely abhor). So far, I have found that the 780G works more to defeat the lows than the highs for me. Am I misunderstanding the system?? I also have gone through around 125 strips in checking my blood sugars which I feel is not a good thing in having a CGM?? Am I doing something wrong on that account?? My A1C since being a diabetic has always been in the normal range, which I am grateful for. I really want this new system to work for me & with me. I have experienced both the Dawn effect & Smogyi effect. As I stated earlier, I really hate the highs & need help in controlling those. After going in the 780G I had a scheduled elective surgery, and I’m recovering nicely from that. My endocrinologist felt at the time that it was best for me to put Smart Guard on hold since I was having difficulty in controlling my highs. Should I go back on the Smart Guard now & why?? Will I be able to get better control on my highs if I do?? I will appreciate any insights or assistance that you can give me! Thank you, Norma

Hi, Norma. We're glad to hear that your surgery went well and that you are recovering! As for your questions about SmartGuard, we would recommend that you work with your healthcare provider to determine the best path forward for you. Thanks!

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