Dawn Phenomenon: How to Identify and Manage It

woman with dawn phenomenon

What Is the Dawn Phenomenon?

The dawn phenomenon is a well-characterized problem that is common in people with and without diabetes. People without diabetes commonly need more insulin in the early hours of the morning to keep their blood glucose levels from rising. This need for more insulin is thought to be due to the natural circadian (biologic cycle of the body) elevations in anti-insulin hormones such as the growth hormone. If you do not have diabetes, the pancreas merely secretes a little more insulin during this time period, which is normally between the hours of 3 a.m. and 7 a.m. However, if your pancreas does not secrete enough insulin because you have diabetes, your glucose level will go up during this time unless you compensate for it. If no extra insulin is provided, the glucose will rise and be high when you wake up. As a person approaches middle age, the dawn phenomenon often declines or disappears entirely. The dawn phenomenon may vary from day to day, making controlling the glucose levels very difficult.

How Do You Manage It?

In order to combat the problem, many teens and adults with type 1 may require a higher basal rate in the predawn hours to counteract the natural increase in growth hormone production. If you have a continuous glucose monitor, you can determine exactly at what time in the early morning your blood sugar starts increasing. People using insulin pumps can take this information and adjust their basal rate appropriately to counteract the issue. Pumps provide temporary basal rates that can be increased or decreased in 1% to 10% increments for 1 to 72 hours as needed for illness, exercise, or other situations like the dawn phenomenon. Having an increased basal rate during the time of the dawn phenomenon is normally very effective at preventing the rise in glucose during those early morning hours. If you are on multiple daily injections and taking a long acting basal insulin, it is very difficult to target and control the dawn phenomenon.

How Do You Know If You Have It?

Testing for the dawn phenomenon is typically done overnight. Have an early dinner and make sure your post meal glucose value is between 120 and 180 at bedtime, with a horizontal trend arrow if you’re on a CGM. This makes it much easier to test your basal dose of insulin. If your glucose values go up overnight to more than 30 mg/dl from your bedtime value, the basal dose my need to be adjusted upward. If your glucose values stay flat until around 3am and then rise, the dawn phenomenon may be present.

It should be noted that not everyone experiences the dawn phenomenon, and on the flip side, in some cases the dawn phenomenon is so strong, no basal insulin at any dose can control it. This is when an insulin pump is truly needed.

The bottom line is that the dawn phenomenon is very common and can be easily treated with insulin pumps that can be programed to increase the basal rate during the early morning hours. If you are on multiple daily injections, the timing of the basal insulin may be important to counteract the issue.

  1. Hello Dr. Edelman, I am a Type 2 and there are times that I wake up in the morning and my reading are over 130. I take one tablet Metformin Hydrochloride 1,000 Mg Tab with my evening meal and I still have highs on some morning not all. Is there any remedies for my problems.

    • Hi Venus,
      130 is not too shabby, but if you go higher on a regular basis, believe it or not you can take the maximum daily amount of metformin all at night as it may reduce your morning highs. There are lots of other choices as well. PLEASE CHECK WITH YOUR DOCTOR FIRST BEFORE MAKING ANY CHANGES! Good luck, and we’d love for you to join our online conference on Nov 7th: https://tcoyd.org/tcoyd-nov-2020/

  2. Any thoughts on other ways to treat or combat morning highs for Type 2s than taking all the metformin at night? Most patients I educate don’t have a pump or CGM and may not even be prescribed insulin. I hear this a lot from my patients when I am assessing their daily challenges in managing their diabetes. I work in an acute care setting and also see out patients for education.

    • Hello Nicole,
      Believe it or not, some patients respond to a small alcoholic drink at or near bedtime that suppresses the liver from producing glucose, also a small snack as the glucose elevation leads to insulin release that suppresses the liver as well. This can work in patients who still have endogenous insulin production. When someone fasts like overnight, the liver starts to pump out glucose which leads to elevated fasting levels.

  3. I Love what you are doing. We will donate to your organization because of the good work you are doing.

    My question is:
    I am on loop with the Omnipod. My problem is, that as soon as I bolus my blood sugar goes up without eating because I followed your advice about blousing 30 minutes in advance, so why is my blood sugar rising without eating???

    • That is unusual. See what’s going on 2-4 hours before you bolus. Were you snacking with no bolus, or exercising at a reduced basal rate and then stopped exercising soon before you were going to eat? The rise in the blood sugar could be from prior snacks with gastroparesis, and/or after exercise, when you get the rebound high. But please get back us. I’m curious what it’s from. It may have something to do with your settings on your loop as well.

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