Early Morning High Blood Sugar? The Dawn Phenomenon vs. The Somogyi Effect

Have you ever gone to bed with a stable blood sugar level, only to wake up with much higher blood sugar than you expected? As frustrating as this may be, it is more than likely explained by the dawn phenomenon or the Somogyi effect.

What is the dawn phenomenon?

Everyone has an internal body clock that helps them wake up in the morning and sleep at night.

As the sun rises, your body releases special chemicals (hormones) to help you wake up and get ready for the day. These hormones tell your liver to release sugar into your blood for energy.

If you have diabetes, your body has trouble handling this extra sugar, which can make your blood sugar go higher than normal in the early morning—this is known as the dawn phenomenon.

What is the Somogyi Effect?

Another cause of high blood sugar readings in the morning is basically the opposite of the dawn phenomenon—it’s called the Somogyi Effect. The result, however, is the same: higher than expected blood sugars in the morning. Sigh!

With the Somogyi Effect, the morning rise in blood sugar is due to low overnight blood sugar levels, known as nocturnal hypoglycemia.

Symptoms of nocturnal hypoglycemia often include:

• Restless sleep
• Nightmares
• Sweating

Low blood sugar at night can happen if you use too much long-acting insulin or exercise a lot right before bed. When your blood sugar drops too low, your body releases hormones. These same hormones are involved in the dawn phenomenon. 

Instead of just waking you up, these hormones cause your blood sugar to rise too high. This is sometimes called a “rebound” high blood sugar. During a rebound high, your body tries to lower your blood sugar, but it can end up making it too high.

Is the dawn phenomenon or the Somogyi Effect impacting you?

Even though it might seem tough, you have power over these situations. By managing your insulin and activity levels, you can stay safe and healthy. The best way to determine whether the dawn phenomenon or the Somogyi Effect is causing your high morning blood sugar is to monitor your levels overnight. 

It may feel tedious or disruptive, but the good news is that you usually only have to do it a couple of nights in a row to understand what’s going on.

Here are some simple steps to help you identify whether your high morning blood sugar is due to the dawn phenomenon or the Somogyi Effect: 

• Start your overnight checks at least three to four hours after your last meal.
• Don’t eat overnight unless it’s to treat low blood sugar with recommended treatment like glucose tablets, powders, gels or gummies. (Remember to stick to Dextrose-based low blood sugar treatments!)
• Avoid drinking alcohol while you’re going through this process.
• Check your blood sugar levels in the middle of your sleep cycle. For example, if you sleep from 11 pm to 7 am, you would check around 3 am. If you skip this step, you will not have enough information to determine what is happening.  
• If you use a continuous glucose monitor (CGM), check your overnight history in the morning. A CGM can help reduce some of the manual labor involved with this process. If you only use a blood glucose meter (BGM), you’ll need to log your readings manually.

Your overnight blood sugar check results should reveal whether you are experiencing the dawn phenomenon or the Somogyi Effect. You may need to repeat your overnight monitoring once or twice to confirm. Let your doctor know your results, too, so they can best support you in solution mode!

How to get through the dawn phenomenon

Because the causes of the Dawn Phenomenon and the Somogyi Effect are different, your problem-solving approaches for each need to be different. 

Here are some approaches to address your morning highs from dawn phenomenon: 

• Try having a bedtime snack: See if it helps prevent your blood sugar from rising unexpectedly in the morning. You can also try different types of snacks and change the amounts of fat, carbs and protein to see what works best. 
• Eat regularly: Don’t go more than six hours without eating. If you wait too long, your body might think there’s a problem and start using its own energy. This can lead to higher blood sugar levels.
• Eat dinner earlier: Lengthening the time between dinner and bedtime gives your body more time to lower your blood sugar after eating. Eat dinner earlier if you can. 
• Be active after dinner: Any activity helps to lower blood sugar. Doing a light physical activity after dinner, like taking a short walk, may be helpful.
• Take medications consistently: Some diabetes medications help control blood sugar that rises overnight due to hormones. To keep your blood sugar steady, it’s important not to miss any doses. You can set an alarm to remind you.
• Discuss your medication timing and dosage with your healthcare provider: Ask whether the timing of your medications around meals is right. Adjusting a dose might help with high blood sugar in the morning. If you use an insulin pump, you can adjust the overnight setting to prevent early-morning blood sugar spikes. You might also need a higher morning dose to help with this rise.

How to get through the Somogyi Effect

If you believe your high morning blood sugars are a result of the Somogyi Effect, here are some ways you can get through it: 

• Count carbs: Be as consistent as possible with your carb servings at night.
• Eat regularly: Skipping meals can lead to low blood sugar if you are taking diabetes medications.
• Avoid alcohol, but if you drink it, be sure to eat a snack: Some people are very sensitive to alcohol and may need to eliminate or reduce it to avoid low blood sugars. Drink in moderation.
• Think about the timing of your activity/exercise: Is evening activity causing your blood sugar to go low overnight? If so, work out earlier in the day.
• Adjust insulin-to-carb ratio: If you are carb-counting, you may need to consult your diabetes care team better to match your insulin dose to your carb intake. Your insulin-to-carb ratio simply defines the amount of insulin you need per gram of carbs. For example, some people have a 1:10 insulin-to-carb ratio, meaning they take one unit for every ten grams of carbohydrate.
• Discuss your medication timing and dosage with your healthcare provider: It’s important to understand how your diabetes medications work and to take them at the recommended times. If you take basal (long-acting) insulin, you may need to discuss adjusting your dose with your healthcare team.

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