The Dawn Phenomenon and Diabetes: Everything You Need to Know

The dawn phenomenon and diabetes: everything you need to know

What a spike in blood-sugar levels during the early morning hours of the day really means.


The dawn phenomenon is the early-morning spike in blood sugar that happens before breakfast.

It is believed to affect more than half of all people with Type 2 diabetes. 

Research into the dawn phenomenon suggests that many people with Type 2 diabetes will experience this and—even though it is a temporary spike in blood sugar—it may have long-term implications for a person’s health. 

Fortunately, the dawn phenomenon can be managed through a combination of medication and lifestyle changes, but it all starts with knowing what the dawn phenomenon is and how it works.

Note: If you’re looking for a way to reduce blood-sugar spikes, check out Pendulum Glucose Control. It’s been clinically shown to lower meal-related blood sugar spikes by up to 32%*.

What is the dawn phenomenon (and what causes it)?

The dawn phenomenon is a term describing a spike in blood-sugar levels during the early morning hours of the day—usually before breakfast—that often occurs in people with diabetes1

This happens because—like most parts of our physiology—blood-sugar levels are influenced by our circadian rhythm2. And that inner clock of ours is set up to anticipate when we need more, or less, energy. 

In order to meet the high energy demands that fuel our body during the day, we turn to food as a source of sugar and other high-energy molecules. 

But when we’re asleep, we still need energy and can’t rely on eating to get it.

During this time, our body will tap into stores of excess sugars and fats that it has collected from previous meals 2,3

In the early-morning hours, the body begins to anticipate when you’ll be waking up and needing energy to go find food. Because it has likely been a while since you last ate, it starts to release sugars into the bloodstream from its energy stores.

As blood-sugar levels begin to rise, the body also releases insulin to prevent them from getting too high1,2,3

This where the dawn phenomenon takes place. 

People with Type 2 diabetes have a harder time controlling their blood sugar, usually because their body can’t produce enough insulin or the cells in their body can’t respond to insulin as well.

Whatever the reason, the end result is the same: Insulin is less effective. 

Because of this, the early morning rise in blood sugar—which is the body’s circadian rhythm anticipating a need for energy upon waking—is not met with a parallel rise in insulin. 

As a result, blood-sugar levels continue to rise even when they shouldn’t, causing a blood sugar spike. 

Is the dawn phenomenon something I need to worry about?

While worrying may not be helpful, the dawn phenomenon is something that people with Type 2 diabetes should be aware of. 

That’s because early-morning spikes in blood sugar may lead to higher average blood-sugar levels and the many health complications that stem from it.  

It has been suggested that the dawn phenomenon may lead to as much as a 0.4% increase in a person’s A1C levels—a measurement of average blood sugar levels over time.

Though this number is small, the effect of such an increase could be long reaching.

Generally speaking, higher A1C levels are associated with numerous health conditions including heart disease, kidney disease, vision loss, and more. 

An increase of just 1% in A1C levels is associated with a 15%-20% increased risk of developing heart disease.1 

The flipside is that a decrease of just 0.8% in A1C levels may decrease a person's odds of heart disease by as much as 45%1

Though you may not experience the dawn phenomenon, many people with diabetes do1 and it is important to recognize when your blood-sugar levels are spiking and to take action to limit the magnitude of the spike—doing so may help limit your risk of developing higher A1C levels and the associated health conditions. 

It is worth noting, however, that controlling stress levels can help you control your blood sugar levels—and that rising stress may cause rising blood sugar. 

So be aware of the dawn phenomenon, talk with your healthcare provider about it, and be proactive; but try not to worry or stress about it. 

Does the dawn phenomenon affect A1C levels?

There is some evidence suggesting that the dawn phenomenon is associated with higher A1C levels6; however, this is a challenging connection to make. 

Chronically higher blood-sugar levels will increase A1C levels. But what effect do temporary spikes in blood sugar have on A1C levels?

It is difficult to know, but one often cited study examined multiple people with Type 2 diabetes and split them into groups based on whether or not they experienced the dawn phenomenon6

The researchers then compared the two groups’ A1C levels and found that the group experiencing the dawn phenomenon had higher average A1C levels. 

This correlation does not indicate causation—meaning it's not clear if it’s the dawn phenomenon causing the higher A1C levels, but it is suggestive evidence. 

More research will be needed to draw a definitive conclusion about whether the dawn phenomenon affects A1C levels. 

Is there a treatment for the dawn phenomenon?

There are ways to counteract the effects of the dawn phenomenon1,5,7; however, few of these have been shown to be effective across the board. 

Put another way, treating the dawn phenomenon will likely require a personalized approach, some trial and error, and most importantly, close consultation with your doctor. 

Most studies focused on treating the dawn phenomenon have been restricted to people with type 1 diabetes and a close examination of how effective certain therapeutics are. As with blood sugar, the amount of therapeutics—such as metformin, or sulfonylureas—in your blood decrease with time. 

Because of this, the medication you take at night may not last into the morning hours and, as a result, can be ineffective at combating the dawn phenomenon1,7

Continuous insulin injections through an insulin pump appears to be the most discussed treatment option because it can provide instant medication at the onset of the dawn phenomenon7

It’s important to note that studies on the dawn phenomenon, and particularly on treating the dawn phenomenon, are still few in number. 

Much more research will be needed to better understand what treatments are effective, safe, and broadly applicable. It is critical, then, to consult your doctor before making changes to your diabetes management. 

Note: If you’re looking for a way to reduce blood sugar spikes, check out Pendulum Glucose Control. It’s been clinically shown to lower blood sugar spikes by up to 32%. 

Does vinegar help control the dawn phenomenon?

Vinegar has been a source of ongoing research with respect to managing blood sugar levels8,9,10.

Preliminary evidence from a study involving 11 people with type 2 diabetes suggests that taking a small amount (2 Tbsp) of apple cider vinegar at night may help reduce blood sugar spikes in the morning—effectively counteracting the dawn phenomenon8

Multiple other studies have been carried out in which researchers examined more broadly if, and how, vinegar may affect blood sugar levels with many finding that vinegar may be beneficial9,10

Taken together, this data suggests that vinegar may be helpful in reducing the dawn phenomenon; however, more studies that specifically focus on timing, quantity, and other contextual factors will need to be done to determine if vinegar truly does have therapeutic benefits in the dawn phenomenon. 

Does Metformin help with Dawn Phenomenon?

Use of metformin in treating the dawn phenomenon has not been widely reported. 

Several studies aiming to treat the dawn phenomenon have included people who were already taking metformin, indirectly suggesting that metformin alone is not enough to manage early morning blood sugar spikes5

Though there isn’t clear research demonstrating that metformin is effective against the dawn phenomenon, there similarly isn’t evidence that it’s not.

In discussing treatment of the dawn phenomenon, the Mayo Clinic suggests shifting the timing of when you take your medication so that it falls closer to bedtime (rather than mealtime)11

It is possible that taking metformin later in the day will help reduce the dawn phenomenon, but there is no clear and reported evidence to support this, yet. 

Are there other methods to help treat the dawn phenomenon naturally?

Some studies have explored non-pharmaceutical approaches to treating the dawn phenomenon, including exercise and diet modifications1,12,13

Though these studies are limited, early evidence indicates that reducing carbohydrates at night may help12. Instead of carbohydrate rich foods—like pasta or white rice—resistant starches or proteins may be better night time meals for individuals experiencing the dawn phenomenon. 

It’s also been suggested that night time exercise, as well as early morning exercise has the potential to reduce dawn phenomenon1,13

Unfortunately, research on the effective treatment of the dawn phenomenon is still too limited to draw firm conclusions on what is most likely to help combat early morning blood sugar spikes. 

What is clear is that keeping a close eye on your blood sugar levels, and consulting with your doctor, are critical steps towards figuring out what treatment regimen is most likely to work for you.

The Somogyi Effect vs Dawn Phenomenon
When learning about the dawn phenomenon, you’ll likely also hear about a related topic known as the Somogyi effect. The two are very similar but differ in important ways.
What is the Somogyi Effect?

The Somogyi effect, like the dawn phenomenon, describes a situation where a person’s blood sugar levels spike in the early morning hours4. However, unlike the dawn phenomenon, the Somogyi effect is preceded by a large dip in blood sugar levels—known as a hypoglycemic event. 

It is important to be aware of the Somogyi effect, because hypoglycemia is also dangerous and if you are experiencing hypoglycemia prior to a blood sugar spike (known as hyperglycemia), your healthcare provider may give you different therapeutic options to avoid severe hypoglycemia.

How Do You Know Which One You Have?

Both the dawn phenomenon and the Somogyi effect are diagnosed using a continuous glucose monitor which records your continuous blood sugar levels1,4,5

In reviewing your blood sugar levels throughout the night and into the early morning hours, physicians can determine if you’re experiencing either of these phenomena. 

Final Thoughts

The dawn phenomenon is a common experience among people with diabetes. 

Research suggests that early morning spikes in blood sugar can contribute to chronically high blood sugar levels and the eventual progression of diabetes into related health conditions. 

Because of this, it is very important for people with diabetes to monitor for the dawn phenomenon and to talk with their doctors about different approaches to treating it. 

Research on this topic is still ongoing, but we do know that it is a common and manageable experience. 

So if you have the dawn phenomenon, know that you are not alone. 

*Reduction in meal-related blood glucose following standard meal.


  1. O'Neal, Teri B. “Dawn Phenomenon.” StatPearls [Internet]., U.S. National Library of Medicine, 29 May 2020,
  2. Ding, Guolian et al. “Central Circadian Clock Regulates Energy Metabolism.” Advances in experimental medicine and biology vol. 1090 (2018): 79-103.  doi:10.1007/978-981-13-1286-1_5 
  3. Kalsbeek, Andries et al. “Circadian control of glucose metabolism.” Molecular metabolism vol. 3,4 372-83. 19 Mar. 2014, doi:10.1016/j.molmet.2014.03.002 
  4. Reyhanoglu, Gizem. “Somogyi Phenomenon.” StatPearls [Internet]., U.S. National Library of Medicine, 10 July 2020,
  5. Porcellati, Francesca et al. “Thirty years of research on the dawn phenomenon: lessons to optimize blood glucose control in diabetes.” Diabetes care vol. 36,12 (2013): 3860-2. doi:10.2337/dc13-2088 
  6. Monnier, Louis et al. “Magnitude of the dawn phenomenon and its impact on the overall glucose exposure in type 2 diabetes: is this of concern?.” Diabetes care vol. 36,12 (2013): 4057-62. doi:10.2337/dc12-2127 
  7. Carroll, Mary F, and David S Schade. “The Dawn Phenomenon Revisited: Implications for Diabetes Therapy.” Endocrine Practice : Official Journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists, U.S. National Library of Medicine, 2005,
  8. White, Andrea M., and Carol S. Johnston. “Vinegar Ingestion at Bedtime Moderates Waking Glucose Concentrations in Adults With Well-Controlled Type 2 Diabetes.” Diabetes Care, American Diabetes Association, 1 Nov. 2007, 
  9. SM;, Johnston CS;White AM;Kent. “Preliminary Evidence That Regular Vinegar Ingestion Favorably Influences Hemoglobin A1c Values in Individuals with Type 2 Diabetes Mellitus.” Diabetes Research and Clinical Practice, U.S. National Library of Medicine,
  10. Siddiqui, Fahad Javaid et al. “Diabetes Control: Is Vinegar a Promising Candidate to Help Achieve Targets?.” Journal of evidence-based integrative medicine vol. 23 (2018): 2156587217753004. doi:10.1177/2156587217753004 
  11. “The Dawn Phenomenon: What Can You Do?” Mayo Clinic, Mayo Foundation for Medical Education and Research, 16 Sept. 2017,
  12. Dyer-Parziale, Maryellen. “The Effect of Extend Bar Containing Uncooked Cornstarch on Night-Time Glycemic Excursion in Subjects with Type 2 Diabetes.” Diabetes Research and Clinical Practice, Elsevier, 30 July 2001,
  13. Zheng, Xin et al. “Effects of Exercise on Blood Glucose and Glycemic Variability in Type 2 Diabetic Patients with Dawn Phenomenon.” BioMed research international vol. 2020 6408724. 21 Feb. 2020, doi:10.1155/2020/6408724 


Sign up to receive healthy-living tips and exclusive offers.