The Dawn Phenomenon and Somogyi Effect: What You Can Do

Waking up with a high blood sugar reading is not exactly the way you want to start off your day. Besides rushing to get ready for work or getting the kids off to school (or both), you now have to decide if and how you’ll deal with that reading on your meter. Maybe you decide to skip breakfast. If you take mealtime insulin, perhaps you inject a few extra units. Or you put in some additional time during your workout. Another option is to shrug it off and hope that your blood sugar comes down in a few hours. You might also ponder the reason your blood sugar is high. Could it be that you ate dinner later than usual last night? Or you ate too much carb at dinner? Or maybe it was your snack?


While it’s normal to have high blood sugars when you have diabetes, it’s time to pay attention when the highs become the norm. Morning hyperglycemia (high blood sugar) is frustrating for many people; figuring out the cause is the first step in dealing with (and preventing) it.

Dawn phenomenon: hormones that wreak havoc

It’s easy to blame your morning high on the plate of pasta last night. But while that could certainly be a factor, chances are, your “highs” are a result of hormones. An imbalance of insulin, amylin (a hormone released by the pancreas), and incretins (hormones released by the gut) is the likely culprit. Other hormones get in on the act, too, including glucagon, growth hormone, cortisol, and adrenaline. Why? Overnight, the body gets this idea that it needs fuel (glucose). The witching hour seems to be around 3 AM or so. At this time, the liver and muscles obligingly respond to the signal for fuel and release glucose into the bloodstream. In someone without diabetes, insulin and its other hormone pals kick in to keep blood sugar levels on an even keel. In the case of diabetes, though, those hormones are pretty much missing in action. End result? Blood sugar levels climb. You wake up, check your blood sugar, and it’s above and beyond the “80–130” range. In case you’re wondering, this cascade of events is called the “dawn phenomenon” or “dawn effect.” It’s estimated that between 10–50% of people with either Type 1 or Type 2 diabetes will experience this at one time or another.

What you can do about the dawn phenomenon

• First, figure out what’s happening overnight. This means, for a few days in a row, setting your alarm for around 3 AM and checking your blood sugar, and then checking again when you wake up at your usual time in the morning. If your blood sugar is within your target range when you check at around 3 AM but is high when you wake up, there’s a high likelihood of the dawn phenomenon going on.

• Rethink your bedtime snack. Some experts recommend avoiding carbohydrate close to bedtime. If you can’t squelch those hunger pangs, try eating a low- or no-carb snack, such as a small handful of nuts, a hard-boiled egg, or raw veggies dipped into nut butter that doesn’t contain sugar. On the other hand, other experts recommend eating about 15–20 grams of carb — doing so may prevent the liver from pumping out too much glucose. Examples include a small piece of fruit, 6 ounces of light-style yogurt, or 3 cups of popcorn. Try out both options and see if either one helps to lower your fasting blood sugar.

• Rethink your diabetes medicine. This can mean changing the time when you take your medicine, whether it’s a diabetes pill or bedtime insulin (meaning, take it at bedtime rather than at dinnertime). You might also benefit from changing the type of medication that you take, or even adding a medication, such as a long-acting insulin. Talk with your health-care provider before you make changes to your medication schedule, and discuss any other options that may be available.

• Consider an insulin pump. If you have Type 1 diabetes or Type 2 diabetes and take both fast and long-acting insulin, using an insulin pump can help you better manage your blood sugars overnight and into the wee hours of the morning.

Somogyi effect: rebounding from a low

The Somogyi effect, also called the rebound effect, is named after Michael Somogyi, a Hungarian researcher who first identified it. The claim behind this effect is that the blood sugar goes low overnight. This drop triggers the release of counterregulatory hormones, such as adrenaline, cortisol, growth hormone, and glucagon, which, in turn, signal the liver to release glucose. The result? Blood sugars rebound and are higher than desired in the morning. The theory, too, is that those hormones create insulin resistance, so that it’s sometimes harder to lower those morning readings.

Interestingly, scientists question the Somogyi effect; some studies have failed to prove its existence. Other studies, however, have shown that this occurrence happens in those with Type 1 diabetes.

What you can do about the Somogyi effect

• If you’re curious about the Somogyi effect and think it could be happening to you, once again, you’ll need to wake up during the night to test it out. A low blood sugar at around 3 AM followed by a high blood sugar when you rise and shine could prove this theory to be correct. You might also have the following symptoms: a rapid heart rate, night sweats, a headache, blurred vision, thirst, and/or dizziness.

• Using a continuous glucose monitor (CGM) is another helpful way to get a picture of what your blood sugars are doing overnight. A CGM checks glucose levels about every five minutes, and also will alert you to either high or low glucose levels, using an alarm.

• The best way to stop the Somogyi effect in its tracks is to prevent it in the first place. This means adjusting nighttime diabetes medication (either your sulfonylurea or your long-acting insulin), making sure you eat enough in the evening (no skipping meals), limiting alcohol intake, and planning for exercise more carefully. Talk with your diabetes educator or health-care provider about options that are best for you.

Morning high blood sugar: more food for thought

• Sure, it’s a pain to have to wake up in the middle of the night to check your blood sugar. Remember, though, that this isn’t forever. If you can do this for at least three nights, you should get a clearer picture of what’s happening. Pick nights when you feel well (meaning, you don’t have a cold or the flu), you aren’t planning to exercise between dinner and bedtime, and your bedtime blood sugar is around 150 or so (not too high, but not too low, either).

• Experiment a little with bedtime snacks, as mentioned above. You may find that not eating a snack helps with your morning blood sugar; on the other hand, eating a reasonable carb-containing snack may help, too.

• Pay attention to high-fat dinners and how they may affect your morning readings. Fat doesn’t directly affect blood sugars, but it can increase insulin resistance and also slow the digestion of carbohydrate. This means that four, six, or eight hours later, you’ll see the effect of that fatty meal on your blood sugars. There’s also some evidence that saturated fat can increase or worsen insulin resistance, as well.

• Don’t overlook the role of stress on your diabetes control, too; recent or extreme stress, whether it be issues at work or at home, an illness, or a recent medical procedure, for example — can affect your blood sugars.

• If you have Type 2 diabetes and you continue to wake up with high readings, don’t be afraid to consider starting, switching, or adding medication, including long-acting insulin, especially if lifestyle changes, such as weight loss, physical activity, and meal planning, aren’t enough to get and keep your blood sugars in a healthy range.

Want to learn more about the dawn phenomenon and Somogyi effect? Read “Controlling the Dawn Phenomenon” and “Somogyi Effect.”

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  • W. Wasylko

    According to research literature, jury is still out on whether Somogyi Effect actually exists.
    So after 49 years as Type 1, I will continue dealing with my Dawn Phenomenon by taking my BG reading at 4 AM & taking corrective insulin dose as required.


    This is a real problem for me in more ways than one. My fasting glucose is always high, usually the highest reading of the day. My A1c, on the other hand is fine and my post-prandial tests are good. The biggest frustration is that my employer requires that we submit to a fasting glucose test once a year, and if that single draw is too high, I have to pay a much larger deductible on my health insurance (they call it “failing to earn a discount” to keep it legal). The dawn effect literally costs me thousands of dollars each year because “failed to meet a personal health care goal” arbitrarily assigned by the insurance company. I have been tempted to skip fasting and eat before the test to bring my readings down, but I don’t like to practice deception. Any ideas other than experimenting with late-night snacks?

    • acampbell

      Hi RAWLCM,
      I’m making an assumption that you take diabetes medication: have you made any adjustments to that? Or considered changing or starting a new medication to help with this issue?

      • RAWLCM

        Hi Amy,
        My primary and endocrinologist generally believe in adjusting overall dosages based on the A1c level. We have tried splitting my dose of long-acting insulin to twice daily, which helped a little for a while. With Metformin as well, instead of twice per day I take a half-dose four times a day. I frequently will have an apple or some raw vegetables if I wake up around 2:00 AM feeling hungry, and the next day my reading will be lower, but that’s not really fasting. It’s extremely frustrating, because I feel I am altering a successful treatment plan to satisfy an insurance company’s arbitrary guidelines. But I stand to lose $6,000 is “discounts” if I don’t meet their goal.

        • evolke


    • ShermanRMcCoy

      Get up, drink a liter of water or two and park about a half mile away from where you have to give the sample. I’ve had readings from 110-128 for as long as I can remember, an A1C of 5.2, but if I do as described, I’m always around 95 by the time I get to the doctor’s office.

  • dufus

    You should address your writing to a general audience instead of only those who, “…rushing to get ready for work or getting the kids off to school (or both),”

  • Amaikin

    — 1st Post
    In my case, morning blood glucose level is quite weird. At wake-up, it is quite ok (around 110), but once I get out of bed and start being active (preparing breakfast, etc.), in the next 15 to 30 minutes, it jumped to about 140-150.
    After wake up, when I stay in bed (even for an additional hour), BG won’t go beyond 120. But once I get out, I see this huge and sudden jump. Don’t know what to do about it.
    I’m a very late night person (rarely go to bed before 2am).
    — Type 2, diagnosed in Mars 2017, with A1C at 10.4
    — Last A1C at 5.4 (early October 2017).
    — Metformin – 500mg / day

    • RAWLCM

      Disclaimer: I’m not a professional, more like an informed patient.
      Going from an A1c of 10.4 to one of 5.4 in six months is pretty awesome. Congratulations!
      There isn’t a consensus on which number is most important. Some believe that if your A1c is in range, not to worry about the occasional fluctuation. Others say it’s imperative to keep your glucose ratings as close to ideal as possible all the time to avoid complications. My doctors are among the former. For me, I would probably suffer more from the stress of trying to maintain tight control than I would benefit from the steady glucose. Every case is unique and you should discuss your concerns with your providers. My Docs don’t consider a rating of 140-150 to be out of goal for me. However I’ve had type 2 for a very long time, and have several other heath concerns. They may have different goals for someone younger, older, or newly diagnosed. The bottom line is always insist on a personalized care plan.
      Like you, I always tended to be a night owl until career choices forced me to flip my schedule on its ear. Actually when I started going against my natural sleep pattern is when I started to see an escalation in heath issues of all kinds. Also like you, I tend to have higher readings in the mornings, especially on work days. Weekends are much more steady.

      • Amaikin

        Thanks for sharing your thoughts.

        Because I find myself at 140-150 before breakfast, after breakfast my BG would jump to 170-180, if not more. And this would take almost 2 hours to come down.
        Will talk to my doctor to see if there is a solution to this.