The Dawn Phenomenon: Managing Morning Highs in Blood Sugar

Roughly half the people with type 1 and type 2 diabetes experience the dawn phenomenon when they wake up. This condition is characterized by elevated blood glucose levels in the morning, with symptoms that could be easily masked under the umbrella of morning exhaustion.

Because of that, the dawn phenomenon may go undiagnosed in most patients. The condition itself isn’t risky. However, its persistence can pose a long-term risk and cause damage to the body because of the effects of hyperglycemia.

This guide explains the dawn phenomenon in detail and how to distinguish it from other conditions with similar symptoms.

Let’s explore the signs you should focus on and report to your doctor so you can work together to manage the morning highs.

The dawn phenomenon is a common condition that happens only to people with diabetes, where the blood sugar levels are abnormally high early in the morning.

The primary cause is the early morning hormonal changes; however, other, compounding causes can exacerbate the symptoms.

The most definitive sign of the dawn phenomenon is the increased blood sugar levels in the morning.

People with diabetes who check their blood sugar in the morning might notice this pattern and detect morning highs, which they can then report to their doctors.

Depending on how elevated the glucose levels are, the following symptoms may also be present:

• A headache that may or may not be accompanied by blurred vision.

• Increased hunger and thirst.

• An urge to urinate that can wake some people up earlier than expected.

• An abnormally irritable mood.

The signs mentioned above can help the person detect that something is off, but the definitive diagnosis is achieved only through blood sugar tests.

When you report these symptoms to your doctor, you’ll mostly be advised to use a continuous glucose monitoring device (CGM), a wearable device that tracks your blood sugar levels without having to prick your finger to use a glucometer.

Once you wake up, look at the CGM display. If your blood sugar levels are persistently high for a few days in a row, you may have the dawn phenomenon.

Another helpful feature of the device is that it can show a graph of how your blood sugar levels rise at night, which can help your doctor better diagnose the case.

The symptoms of the dawn phenomenon are quite similar to another morning condition called the Somogyi effect . Both the dawn phenomenon and the Somogyi effect happen because of hormonal changes, but the cause is different.

The dawn phenomenon occurs because of natural hormones your body makes in the morning, including growth hormone and cortisol.

The Somogyi effect occurs after a low blood sugar episode overnight, in which the body tries to overcompensate by releasing hormones that trigger the liver to release stored glucose.

In other words, the dawn phenomenon occurs because of a natural hormonal cycle regardless of any physiological or pathological changes, while the Somogyi effect is a corrective response to low blood sugar levels during sleeping.

Since the symptoms are the same, it can be difficult to distinguish between both conditions based on the symptoms alone, which is why a CGM is recommended.

The graph provided by the CGM is beneficial in differentiating between the dawn phenomenon and the Somogyi effect, which is another condition that can cause blood sugar to rise in the morning.

Treatment for both conditions involves managing blood glucose levels at night, but the approach differs.

Between 3 AM and 8 AM, our bodies naturally release growth hormone and cortisol. These hormones and others signal your liver to release some of its stored glucose to help wake you up.

In a person who doesn’t have diabetes, the pancreas will respond to this by releasing insulin, which helps your cells uptake circulating glucose, preventing hyperglycemia.

However, people with diabetes don’t have the same response. In the case of people with insulin-dependent diabetes, the pancreas doesn’t make any or enough insulin to handle that rise in blood sugar.

In some cases of type 2 diabetes, insulin resistance prevents the cells from utilizing the circulating glucose because of their decreased sensitivity to the hormone.

The dawn phenomenon causes constant high blood glucose levels in the morning, which can result in complications in the long run. A 2013 study concluded that the dawn phenomenon increases HbA1c levels by around 0.4% over three months.

The increased HbA1c levels increase the risk of diabetic ketoacidosis, retinopathy , and neuropathy — all of which are dangerous conditions.

Here’s how you can mitigate this rise and prevent complications:

Depending on their condition, a person with diabetes could be taking multiple medications. These include insulin, biguanides, dopamine-2 agonists, Dipeptidyl peptidase-4 (DPP-4), alpha-glucosidase, and GLP-1 receptor agonists.

To adjust the dose, it takes multiple trials, coordinated with your healthcare provider, to eliminate or at least reduce your morning highs to an acceptable level.

For people with insulin-dependent diabetes who don’t have insulin resistance, an insulin pump can be a feasible solution. Your doctor can help you adjust the insulin pump to provide an extra dose/amount of insulin in the early morning hours when high blood sugar levels usually appear.

To prevent hypoglycemia as a result of overestimating the dose, wearing a continuous glucose monitor for a fair period before using an insulin pump can be beneficial. It should help you understand the pattern of high morning blood sugar when you can safely administer extra insulin.

People living with medication-treated type 2 diabetes should try the insulin resistance diet to keep their blood glucose controlled throughout the day.

They should also be extra careful with the timing and carb content of their evening meals to prevent the liver from having a large store of glycogen, fueling the morning highs.

To avoid raising your glucose levels, you can start by avoiding carbohydrates at least two hours before you sleep. This strategy is called nocturnal blood glucose control.

If your last meal contains carbohydrates, focus on complex carbohydrates (whole grains) over refined ones. Complex carbohydrates include brown rice, barley, black beans, and oats. They take longer to digest and release into the bloodstream.

Sugary beverages should also be avoided with diabetes, especially before bedtime. Drink large amounts of water throughout the day as it helps to reduce the glucose concentration in your bloodstream.

Being active can help increase insulin sensitivity , which is especially beneficial for people with type 2 diabetes who get elevated morning blood sugar because of insulin resistance.

Make the habit of lightly exercising 30 minutes before sleep to help your body use up some of the stored glycogen in the liver.

However, if you have type 1 diabetes, don’t go overboard with your nightly exercise to avoid risking hypoglycemia. Focus on light activities, like walking or yoga.

The dawn phenomenon happens because of a natural hormonal action in your body, so the best you can do is reduce its impact and prevent its complications.

High blood sugar in the morning could be caused by a variety of factors, so using a nighttime CGM can help you and your healthcare provider pinpoint when the issue arises.

There are three episodes of high blood sugar that you can experience during sleep:

If data from your CGM indicates that your blood sugar is already high by the time you go to bed, then the reading you get in the morning isn’t due to the dawn phenomenon. It’s mostly because of high-carb food and inadequate dosing of your medication.

Large dinners and bedtime snacks are possible culprits; whereas too-low insulin or oral antidiabetics with your last meal are medicine-related culprits.

Based on this data, your doctor will recommend a lighter dinner and/or adjust your medication dose.

If your data suggests that your blood sugar is fine when you sleep but starts to rise a couple of hours later, then it’s mostly a medication issue.

You may take long-acting insulin in the morning, whose effect wears off when you fall asleep.

Based on this feedback, your doctor may switch your insulin to a twice-daily dose, prescribe an ultra-long-acting insulin, or change the timing of your dose.

If your data says that your blood sugar starts rising only after 3 AM, you’re most likely experiencing the dawn phenomenon. Increasing your long-acting insulin won’t be recommended at this point. It may reduce morning hyperglycemia, but it can also risk hypoglycemia.

In most cases, the best recommendation your doctor can give you is using an insulin pump. With the help of your doctor, you can program it to release an extra dose of insulin in the morning when the dawn phenomenon occurs.

Unfortunately, this solution is more useful in insulin-dependent diabetes with no insulin resistance, as the cells have no problem utilizing insulin when it’s present in the bloodstream.

However, a healthy diet, exercise, and stress reduction can increase insulin sensitivity in people with medication-assisted type 2 diabetes, lowering their overall glucose exposure and helping them mitigate the dawn phenomenon.

Living with the dawn phenomenon can sometimes be challenging to handle, and not everyone manages to eliminate it entirely.

Using the information in this guide, you should be able to isolate the cause and optimize blood glucose control. If the problem is because of your medications or insulin, you should always consult your doctor before adjusting them to avoid potential risks.

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