In Categories: Practical Tips

Are you noticing that your blood glucose is highest in the morning when you wake up and you haven’t even had anything to eat yet? Don’t worry! This is a very common effect known as the dawn phenomenon. Let’s take a look at the science behind this phenomenon and explore strategies to help you reduce your fasting glucose.

What causes the dawn phenomenon?

The dawn phenomenon, sometimes referred to as the “dawn effect,” has earned its name from the recurrence of elevated blood glucose (a.k.a. sugar) around the hours of waking, roughly between 4-8 AM. Although the exact underlying causes of the dawn phenomenon are still unclear, it is known that hormones, including adrenaline, cortisol, glucagon, and growth hormone, play a large part. These hormones follow a circadian rhythm, or a daily cycle, and tend to be found in higher concentrations in the blood in the morning to help prepare us for the day ahead.

The hormones that promote glucose release into the blood include:

  • Adrenaline: Known as the “fight or flight” hormone, adrenaline increases blood flow to the muscles and promotes the release of glucose into the blood.
  • Cortisol: Known as the “stress hormone”, cortisol also plays a role in increasing blood glucose.
  • Glucagon: Signals the liver to release glucose into the blood.
  • Growth Hormone: Important for repair and regeneration and promotes the release of glucose into the blood.

Two key processes occur in the liver overnight that result in the release of glucose into the bloodstream and contribute to increased morning blood glucose:

1) Glycogenolysis, the breakdown and release of stored glucose (a.k.a. glycogen)

2) Gluconeogenesis, the creation of glucose from components of protein (i.e. certain amino acids) or fat (i.e. glycerol)

One more hormone that plays an important role is insulin. When blood glucose rises, insulin is released and helps move glucose out of the blood and into cells for energy use or storage.

Does the dawn phenomenon occur only in people with prediabetes and type 2 diabetes?

The physiological processes that underlie the dawn phenomenon occur in everyone regardless of whether they have diabetes or not. The difference lies with insulin and how our bodies react to it. Healthy individuals secrete enough insulin and are insulin sensitive enough to counteract a rise in morning blood glucose. However, someone with prediabetes or type 2 diabetes is insulin resistant and/or may not secrete enough insulin, which allows blood glucose to rise. This may be further compounded in the early morning hours because our body is more insulin resistant compared to the rest of the day,1 causing an elevated fasting glucose to remain elevated longer. Progression of prediabetes and type 2 diabetes is likely to result in a worsening of the dawn phenomenon as insulin function and sensitivity continue to diminish.

Is the dawn phenomenon something I need to fix?

The dawn phenomenon is not necessarily something that needs to be fixed. It’s important to keep in mind that even though your fasting glucose may be elevated, you may have lower or normal glucose values throughout the rest of the day. Additionally, it’s not uncommon for patients reversing their diabetes through nutritional ketosis to experience the dawn phenomenon and still see improvements in their HbA1c. Why? Because HbA1c is a measure of your blood glucose over the last 3 months. The average value matters more than any individual blood glucose value.

Example blood glucose curve of someone controlling their type 2 diabetes through nutritional ketosis who experiences the dawn phenomenon2

Dawn phenomenon blood sugar graph

How can I combat the dawn phenomenon? Will reducing my carb intake help?

If you want to understand if elevated morning blood glucose numbers are a result of the dawn phenomenon or from too many dietary carbohydrates, all you need to do is test at multiple times throughout the day. First and foremost, you should be familiar with what your fasting glucose looks like. Whether it be your most recent lab values from the doctor or checking your glucose with a meter, the best way to know where your fasting glucose falls is to measure it, and to test it on a few different days. Similarly, testing your glucose throughout the day, before and after meals, and before you go to bed can help you understand how your body responds to the food you eat.

Once you’ve tested enough that you understand your baseline glucose with your current habits, try incorporating each of the strategies outlined below into your routine. Continue testing your blood glucose and you’ll see what impact each change has on your morning fasting glucose.

Strategies that may help mitigate the Dawn Phenomenon:

  • Get a good night of sleep—6 to 8 hours each night—and go to bed before midnight to help reduce cortisol and improve one’s ability to tolerate glucose.3
  • Reduce your overall carbohydrate intake* (always with medical supervision) to lower blood glucose.
  • Eat dinner earlier in the evening and avoid late night snacks to reduce blood glucose in the evening.
  • Have your last meal of the day contain the least amount of carbohydrates to minimize the rise in blood glucose.
  • Do something active after dinner, such as a walk, to help lower blood glucose.
  • Eat a breakfast a lower in carbohydrates since blood glucose is high and you have greater insulin resistance in the morning.
  • Don’t wait too long to eat breakfast when you wake up. Eating food early in the morning can help release insulin which can lower blood glucose

A note about safety

*I do not recommend that people with diabetes or prediabetes make large-scale dietary changes without medical supervision, especially if taking medications for diabetes or blood pressure. Reducing carbohydrate consumption can decrease blood glucose and blood pressure, and a physician can help safely adjust medications so that blood glucose or blood pressure don’t get too low. Hypoglycemic (low blood sugar) and hypotensive (low blood pressure) episodes can be very dangerous.

To learn more about how food affects blood sugar, check out Dr. Sarah Hallberg’s video series here:

16 Comments

  1. I have the exact issue. high fasting BG up to 125, and a1c of 5.7.
    do you recommend fasting?
    if yes, then i cant have breakfast. i have been trying to IF for 16/8 daily
    .thanks

    Reply

    1. Virta Health

      We don’t recommend fasting. Try the tips in this post!

      Reply

  2. I have a problem with the dawn phenomenon kicking me out of nutritional ketosis every morning. I have been eating a ketogenic diet fully for 1 1/2 months. (A month before that I began easing my way into it by lowering carbs. Then I had to lower protein while I increased fat).

    I have T2 diabetes. I take 500 mg of metformin bid 12 hours apart. My keto stix have been showing me in ketosis, even in the morning. However I recently purchased a keto mojo to measure my blood ketones. Last night I was at 1.5 and at 6:45 am this morning waking up it was 0.4. I took it again to see if it was a fluke and it was 0.2! My blood sugar upon waking was 114. I didn’t eat breakfast or take my metformin until 7:45 am.By that time it was 125! I ate a high fat breakfast with 7 net carbs and moderate protein. 2 hours later my blood sugar was 123 and my ketones were 0.4 It took me until 11:00 to hit 1.1 ketones and bl glucose of 94. My glucose will stay pretty stable around 90-105 all day after that, even after meals.

    How do I conquer this dawn phenomenon? I’ve tried high fat snack or no snack, dinner at different times, 16:8 fasting and no fasting. Is eating all my calories in 2 meals a day 12 hours apart ok?

    My levels are lower during the day and evening. Should I eat take my evening metformin with dinner later around 8? I hate eating late because of acid reflux. Its frustrating!

    I know you do not recommend fasting and I tried pushing breakfast later and my blood sugar keeps going up well into 120’s til I eat and take metformin. So I can say for me a 16:8 fasting program does not work!

    Reply

  3. Mariann Woods July 27, 2018 at 2:31 am

    I need to loose weight I have been a type two for about 15 years!!, I lost a lot on a diet called true balance eating lunch and supper fruit, five cups veggies and one serving protein no salt no oil, no chemicals!! But I gained it right back when I started having gastro issues!!, I also took metabolic drops, seven seas veggies and detox drops when I stopped supplements and started adding things back in here come the pounds!! A1c is 7.2 now and was way down!! I am very confused about no fats need fats…… I want to be healthy with no co placating from diabetes down the road!! Have a strong family history of heart disease!! I would love instructions for yum program

    Reply

    1. Virta Health

      Hello! You can learn more and apply here: https://www.virtahealth.com/thevirtatreatment

      Reply

  4. I am 5’3 125 lb waist relaxed 26”/27” . Been doing keto 15 months and every morning my precision extra reads 110 average. 120 sometimes and even 130 sometimes does not go higher from 7am-11pm. I am sleeping a lot better. Ketones average 6. I average 20 carbs. I tried FINALLY to give up coffee 10 days ago as a last resort. That was ugly, but so far no difference maybe takes more time. I worry it will get worse. Oh I am 72 years old…

    Reply

  5. My numbers have increased a lot recently from approx fasting in morning was 140 now it’s been around 250 in the morning. I eat approx 60 carbs a day,I exercise 90 minutes every day. I use to weigh 230 now 180 been that for about ten years. Been on the keto diet for about two years. Last night I woke up at 2am checked blood sugar was 162 went back to bed woke up and checked 182 so yes mine has been raising in the morning? Help please I want to fix it thanx.

    Reply

    1. Virta Health

      Hi Larry, have you tried the all strategies listed in this article? Hopefully these will help.

      Strategies that may help mitigate the Dawn Phenomenon:

      Get a good night of sleep—6 to 8 hours each night—and go to bed before midnight to help reduce cortisol and improve one’s ability to tolerate glucose.3

      Reduce your overall carbohydrate intake* (always with medical supervision) to lower blood glucose.

      Eat dinner earlier in the evening and avoid late night snacks to reduce blood glucose in the evening.

      Have your last meal of the day contain the least amount of carbohydrates to minimize the rise in blood glucose.

      Do something active after dinner, such as a walk, to help lower blood glucose.

      Eat a breakfast a lower in carbohydrates since blood glucose is high and you have greater insulin resistance in the morning.

      Don’t wait too long to eat breakfast when you wake up. Eating food early in the morning can help release insulin which can lower blood glucose

      Reply

  6. Hi I recently tried intermittent fasting and tested at 170 in the morning after an overnight fast 16 hours. Will this improve with time?

    Reply

    1. Virta Health

      We generally recommend against fasting for longer than 24 hours, and we recommend informing your physician if you’re fasting while taking medications for diabetes or blood pressure. More info here: https://blog.virtahealth.com/science-of-intermittent-fasting/

      Reply

  7. I noticed that all ketogenic diet questions have been ignored yet the ketogenic diet is used to reverse T2 successfully and is recommended. I’m just wondering why? Have your medical studies not included a ‘strict’ 5% carb 25% protein 70% fat long term study? If not then this needs to be the very next thing to do as you’re not giving up to date medical advice.

    Reply

    1. Virta Health

      The Virta treatment utilizes a ketogenic nutritional intervention supported by one-on-one health coaching, medical supervision by a Virta provider, educational resources and a supportive patient community. You can find our published studies here: https://www.virtahealth.com/research

      We also have a keto FAQ: https://blog.virtahealth.com/nutritional-ketosis-faq/

      Reply

  8. I haven’t been diagnosed with prediabetes. Nonetheless my fasting sugar level is usually around 100 (+-5) if measured exactly after waking up. If I wait 15 minutes or so it goes down to 85. The rest of the day my glucose levels never exceed 120 after meals. Is this normal?

    Reply

    1. Virta Health

      The dawn phenomenon can affect anyone, whether or not they have diabetes.

      Reply

  9. hi. i’m a T1, and i’ve been meticulously recording my blood sugars and food. i noticed that i experience dawn phenom a lot but there are also days when i don’t. my diet is pretty much the same everyday, average 75g carb a day (15-30-30, not much room for change here). i don’t do any diet besides low carb.
    so i’m curious about what exactly triggers the dawn phenomenon? i understand that everyone gets that “boost” to wake up, but why not everyday? or, how sensitive to triggers is the phenomenon? hoping to get some answers for this lifelong journey, thanks~

    Reply

    1. Virta Health

      Poor sleep, inflammation, illness and stress can all cause increases in fasting blood sugar that may contribute to the higher levels you occasionally see.

      Reply

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