One stubborn thing about a life with diabetes is that you’re more likely than not to experience morning high blood sugar levels. 

It can be frustrating to wake up with high blood sugar when you feel as if you’ve done nothing wrong (not to mention that you haven’t even eaten anything yet for the day!). 

What can be the cause of these hyperglycemic episodes? Is it Dawn Phenomenon? The Somogyi Effect? A bent insulin pump cannula or eating while sleepwalking? 

This article will describe the different reasons why your morning blood sugar may be high and what you can do about it. 

Man sitting in bed looking tired

What is considered high blood sugar in the morning? 

Always talk with your doctor about your individual blood sugar goals, because they can vary across one’s lifespan (and differ depending on whether or not you’re pregnant, sick, or going through a hormonal or life change). 

Normally, however, fasting blood sugar levels for someone with diabetes should be somewhere between 70-130 mg/dL. 

High blood sugar levels routinely above that are considered hyperglycemic. Anything above 180 mg/dL after your initial meal of the day is the benchmark for hyperglycemic blood sugars when not fasting. 

What is the Dawn Phenomenon? 

The Dawn Phenomenon is a biological process that dates back to prehistoric times. It evolved to occur so humans have more energy in the morning (and thus more sugar in the blood) to fuel their days..  

The Dawn Phenomenon is a hormonal shift in the body of the overnight release of counter-regulatory hormones, like growth hormone, adrenaline, cortisol, epinephrine, and glucagon. 

This results in morning insulin resistance that can result in higher blood sugar levels between 2 a.m. and 8 a.m., but it can offset your entire day, and leave you frustrated, hungry, and suffering from prolonged high blood sugar levels that are not healthy over the long-term. 

People without diabetes have Dawn Phenomenon as well, but their pancreases increase insulin secretion to prevent high blood sugar levels. 

It’s estimated that over 50% of people with diabetes suffer from Dawn Phenomenon. However, it is more common in people with type 1 diabetes than people with type 2 diabetes, and most noticeable in people who are on insulin therapy. 

What is the Somogyi Effect? 

The Somogyi Effect, on the other hand, is the body’s reaction to a low blood sugar experienced overnight, where the liver releases glucagon to bring the blood sugar back up in an emergency situation, usually resulting in extremely high blood sugar levels. 

This can also be called Rebound Hypoglycemia. 

This is very common in people with insulin-dependent diabetes, because manually dosing insulin to manage blood sugar levels is not a perfect science, and experiencing low blood sugar levels while you sleep is characteristic of a life lived with diabetes. 

The Somogyi Effect is most common in people with type 1 diabetes and insulin-treated type 2 diabetes. 

How can you tell the difference between the two conditions?

Telling the difference between the two conditions can be key to helping prevent the resulting high blood sugar levels from harming you in the first place. 

If you wear a continuous glucose monitor (CGM) device, scan through the hours during which you were asleep. 

If you see a steady rise of blood sugar between the hours of 2 a.m. and 8 a.m. over several days or weeks, while having normal blood sugar levels of between 70-130 mg/dL before you went to bed, you’re most likely experiencing the Dawn Phenomenon. 

If you scan through your blood sugar levels and notice a sharp drop in blood sugar overnight and then a sudden spike (without treating your hypoglycemia), signs lead to the Somogyi Effect.

This happens when your liver dumps glucose into the bloodstream to prevent a prolonged and dangerous low blood sugar. 

If you don’t have a CGM, you’ll need to wake up in the middle of the night between 2 a.m. and 8 a.m. and test several times to see where your blood sugars are trending. 

You may want to set some alarms to wake up hourly to see whether you’re going low during those hours or inching higher to determine whether you’re experiencing the Dawn Phenomenon or the Somogyi Effect. 

How can you prevent these conditions from occurring? 

Since these two conditions have different causes, they will require different interventions to solve. 

Some ways to help prevent the onset of the Dawn Phenomenon include:

  • Don’t eat a carbohydrate-rich snack or meal before bed
  • Exercise before bed instead of in the morning or during the day 
  • If you’re on multiple daily injections, change your long-acting insulin to an evening dose instead of a morning dose, so it’s not tapering off throughout the night (or split your dose in two – morning and evening)
  • Talk to your doctor about increasing your insulin-to-carbohydrate ratio and correction factor (CF) to be more aggressive in your bolusing
  • Use an insulin pump and set more aggressive basal rates throughout the night 

Some ways to prevent the onset of the Somogyi Effect include: 

  • Exercise in the morning instead of in the afternoon or evening
  • Have a lower carbohydrate snack or meal in the evening, so you’ll have less insulin on board at bedtime 
  • Pair a high fat, high protein snack at bedtime, to help maintain blood sugar levels (think peanut butter with celery)
  • Use an insulin pump and take advantage of temporarily lowering your basal rates overnight to avoid low blood sugar levels 
  • Talk with your doctor about adjusting your insulin-to-carbohydrate and correction factor (CF) ratios to be less aggressive in the evening to avoid low blood sugar levels 

You can learn more about strategies for avoiding high morning blood sugars in our guide: How to Avoid High Morning Blood Sugar


Both the Dawn Phenomenon and the Somogyi Effect are common conditions experienced by people who have diabetes, especially insulin-dependent diabetes. 

Although the conditions result in the same outcome, high blood sugar levels in the morning, they have vastly different causes. 

The Dawn Phenomenon is a natural biological release of hormones between the hours of 2 a.m. and 8 a.m. that increases insulin resistance and means higher blood sugar levels upon waking.

The Somogyi Effect, on the other hand, is a rebound high blood sugar, resulting from the liver dumping glucose into the bloodstream to treat a severe low blood sugar experienced overnight. 

These issues can be frustrating, and over time, may contribute to diabetes complications, which should be avoided at all costs. While not completely preventable, their severity can be mitigated with some strategic tactics. 

Taking preventive measures before going to bed, such as either increasing or decreasing your basal and bolus settings and the time at which they’re taken, adjusting your bedtime snack and evening meals, and figuring out what time during the day is best for exercise can help you mitigate these common but stubborn morning high blood sugar levels. 

Talk with your doctor before adjusting your insulin doses to figure out the most appropriate settings for you and your health goals.