Possible Causes of Morning Highs

Do you ever just wake up in the morning and check your blood sugar only to find that it’s higher than 125 mg/dL? You were sure you did everything right the night before and yet your sugar is still high. Maybe it’s been high for the past week or two and you don’t know why. There could be a reason behind your morning highs. Two theories that scientists have come up with are the Dawn Phenomenon and the Somogyi Effect. Let’s begin!

The Dawn Phenomenon

Also called the dawn effect, is described as an abnormal early-morning increase in blood sugar – usually between 2AM and 8AM that occurs regularly in diabetics. The occasional high isn’t much of a worry, but when it happens almost every day, it’s an issue.

There is a natural overnight release of counter-regulatory hormones – the growth hormone, cortisol, glucagon, and epinephrine – that increases insulin resistance, causing blood sugar to rise.

High morning blood sugar may also be caused by not enough insulin the night before, low dosage of diabetes medication, or eating a carb-heavy snack at bedtime.

What You Can Do

If you suspect the Dawn Phenomenon, consult with your doctor. Your doctor may make some recommendations to help prevent or correct your high morning blood sugar levels:

  • Avoid carbs at bedtime
  • Eat regular meals (stay consistent with meals per day, times of day, etc.)
  • Adjust your dose of medication or insulin
  • Eat dinner earlier in the evening
  • Switch to a different medication
  • Do some light exercise after dinner, like walking, jogging, or yoga
  • Change the time you take your medication or insulin from dinnertime to bedtime
  • Use an insulin pump to administer extra insulin during early-morning hours

Personally, I have moved from taking my insulin at a set time each night to within one hour of falling asleep. Once I start feeling tired, I inject my insulin. So far my levels have been lower than when I take it at 9:30pm.

The Somogyi Effect

Also known as the rebound effect, is another possible cause of high blood sugar in the morning. Not all scientists believe this effect is real, but it happens when blood sugar levels drop too low.

If a diabetic were to take insulin without a bedtime snack or inject too much insulin, their blood sugar levels may drop during the night. The body then responds by releasing growth hormones that trigger sugar levels to go back up causing blood sugar levels to be high in the morning.

The Difference Between the Two

The biggest difference between the Dawn Phenomenon and the Somogyi Effect is that the Somogyi effect includes a decrease in glucose levels causing hypoglycemia which is then followed by a rebounding hyperglycemia.

The easiest way to find out which one is causing your high glucose levels in the morning is to record you blood sugar throughout the night. Take your sugar before bed, then again at 3AM in the morning, and then once more when you wake up in the morning.

If your 3AM reading is low, there’s a likelihood that the Somogyi Effect is the cause. If your 3AM reading is normal or high, then it is likelier to be the Dawn Phenomenon that caused your morning highs.

The only way to be sure is to do this process of at least three readings each night for at least one week. The longer you do it, the more familiar with your body you become. Then relay this information to your doctor and they will be able to work with you to correct these morning highs.


Mayo Clinic
Medical News Today

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