What Is Dawn Phenomenon?
Dawn phenomenon is an increase in blood sugar levels that takes place early in the morning in people with diabetes.
If you have diabetes and wake up very thirsty, starving, cranky, and with an urgent need to pee, it may be because your blood sugar soared during the early morning hours. The reason for this rise in your levels could be the dawn phenomenon, which affects more than 50% of all people with diabetes at one time or another.
What Causes Dawn Phenomenon?
It occurs because diabetes interferes with your body’s ability to respond to normal hormonal changes that happen in the early hours. Between 3 a.m. and 8 a.m., your body releases hormones that are designed to boost your blood sugar and give you energy to start your day when you get up. That happens whether you have diabetes or not. If you don’t, your body produces more insulin, which allows your cells to use blood sugar for energy. You don’t even notice that it’s happening.
But if you have diabetes, it’s different. Since your body either doesn’t make enough insulin (type 1 diabetes) or doesn't respond to insulin as effectively as others (type 2 diabetes), your fasting blood sugar level can go up, even if you follow a strict diet. That disrupts the delicate balance that you work so hard to keep, and your sugar readings can be too high by morning, resulting in dawn phenomenon.
The effects of dawn phenomenon can vary from person to person, even from day to day.
You may also have high blood sugar in the morning because:
- You didn't have enough insulin the night before.
- You took too much or too little medicine.
- You ate the wrong snack before bedtime.
- The Somogyi effect, which happens if you inject too much insulin, causes your blood sugar to dip low overnight, and your body reacts by churning out too much blood sugar.
Symptoms of Dawn Phenomenon
The surest sign of having dawn phenomenon is that your blood sugar readings are consistently high in the morning. You can find out by waking in the early hours (around 3 a.m.) and checking your levels with a glucometer. If you use a continuous glucose monitor, which monitors blood sugar levels around the clock, you can use that data to detect dawn phenomenon. If you have diabetes, chances are your blood sugar will be higher in the morning from time to time. That may not be something to be overly concerned about. But if it happens for several mornings in a row, tell your doctor.
If you have these symptoms when you wake up, it could mean you have dawn phenomenon:
- You’re intensely thirsty and hungry
- You need to pee a lot
- Your head is pounding
- You’re irritable
- Your vision is fuzzy
Don’t try to diagnose dawn phenomenon on your own. If you have persistent symptoms or your blood sugar numbers are usually high in the morning, tell your doctor. They can figure out if you really have dawn phenomenon, or if something else is causing those higher morning numbers.
Dawn Phenomenon Treatment
If you are struggling with dawn phenomenon, your doctor may recommend using an insulin pump. An insulin pump is a small device you wear on your body that delivers a steady flow of insulin throughout the day. Your doctor can show you how to program an insulin pump to deliver extra insulin early in the morning, while you’re sleeping.
If you don’t use an insulin pump, work with your doctor to come up with a plan to prevent or minimize dawn phenomenon and other causes of high blood sugar in the morning. Adjusting your medication regimen may help, but keep a few things in mind. For one, if you use insulin, you may be tempted to increase your long-acting insulin dose to maintain your levels until morning. However, that could cause a steep drop in blood sugar after you hit the hay, which could be dangerous. Also, there’s little evidence that oral diabetes medications are effective for controlling dawn phenomenon.
Some lifestyle changes that may be useful include:
- Eat dinner earlier in the evening.
- Do something active after dinner, like going for a walk.
- Eat breakfast. It helps bring your blood sugar back to normal, which tells your body that it's time to rein in the anti-insulin hormones.
You should also avoid all sugar-sweetened beverages, such as soda, fruit punch, fruit drinks, and sweet tea. Just a single serving can raise your blood sugar -- and, in some cases, give you hundreds of extra calories.
Is Dawn Phenomenon Dangerous?
Feeling bad when you wake up because your blood sugar spiked while you slept isn’t typically a medical emergency. However, if you have dawn phenomenon and don’t take steps to curb it, you could be asking for trouble. That’s because having dawn phenomenon means that your blood sugar frequently remains high for at least several hours a day. Over time, untreated high blood sugar damages tissues in your body. If you have consistently elevated blood sugar you have an increased risk for potentially serious diabetes complications, including:
- Retinopathy, which damages your retina, an important tissue at the back of your eye
- Nephropathy, a progressive form of kidney disease
- Neuropathy, or damage to your nerves
- Heart disease, including coronary artery disease (clogged arteries), heart failure, and cardiomyopathy, which affects your heart muscle
If you think you may have dawn phenomenon, talk to your doctor soon.
Takeaways
If you have diabetes, there’s a good chance you will experience dawn phenomenon at some point. A spike in blood sugar while you sleep can leave you feeling miserable in the morning, but over time, dawn phenomenon can also increase your risk for serious diabetes complications. If you suspect you may have dawn phenomenon, talk to your doctor. There are some simple ways to find out if your blood sugar is too high in the early morning hours. By working with your doctor, you can find strategies that control dawn phenomenon.
Dawn Phenomenon and FAQs
How do I stop high blood sugar in the morning?
If your blood sugar readings are consistently high in the morning, tell your doctor. They can help you find out why your blood sugar rises in the hours before you wake up and recommend adjustments to your medication regimen and daily routine that can help prevent dawn phenomenon and other causes of high blood sugar in the morning.
Why is my blood sugar level high when I wake up?
Your blood sugar level may be high when you wake up due to dawn phenomenon, which affects about half of all people with diabetes. Your body naturally releases glucose (sugar) into the blood in the early morning hours, which provides you with energy to start your day. Normally, insulin maintains a steady level of blood sugar. But if you have diabetes, you may not make enough insulin or your body may resist its effects. As a result, you wake up with high blood sugar. You may also have high blood sugar levels overnight because your medication regimen needs an adjustment or due to the meal or snack you had before going to bed.
What is too high for morning blood sugar?
If you have diabetes and routinely check your blood sugar, your doctor can tell you if it’s too high in the morning. No two people with diabetes are alike, so a morning blood sugar level that’s too high for you may be acceptable for someone else. Again, your doctor can tell you what range your blood sugar should be at different times of the day, especially before and after meals. The American Diabetes Association recommends that for most people with diabetes, a healthy blood sugar range before you eat breakfast or any other meal is between 80 and 130 mg/dL.
How soon after waking up should I test my blood sugar?
If you use insulin, the usual recommendation is to check your blood sugar before you eat breakfast or any other meal.
How to lower A1c overnight
If you have high blood sugar overnight, your doctor can help you identify the cause and recommend a strategy for lowering it. The A1c test can’t show that you have high blood sugar overnight, however. It measures your average blood sugar level over the last few months. Instead, you can use a glucose meter or continuous glucose monitor to find out if you have high overnight blood sugar.
