Somogyi Effect: What It Is and What Causes It?

Somogyi effect

The Somogyi effect is another possible wrinkle in the management of your blood sugar. If you wake up with a headache, blurred vision, night sweats… The list of symptoms below will tell you more. And if any of it seems to fit you, see your doctor.

What Is It?

The Somogyi effect is an overnight hormonal rebound. In other words, you go to bed with hypoglycemia and wake up with hyperglycemia. It’s somewhat controversial based on ambivalent research findings. But diabetics and their treating physicians can point to some studies to confirm it.

It’s sometimes confused with the dawn effect. The dawn effect also results in morning hyperglycemia but the cause is different. It’s worth noting that one study of type 1 diabetics found the Somogyi effect to be the most common cause of fasting hyperglycemia.

One way to distinguish between the two is to test your blood glucose somewhere between 2 and 3 am. If your glucose levels are low, that indicates Somogyi. If they’re normal or high, it’s likely the dawn effect. In fact, this is a motivation for looking into continuous glucose monitoring.

What Causes It?

In simplistic terms:

  • Hypoglycemia puts your body under stress.
  • Stress causes the release of stress hormones and glucagon.
  • Glucagon causes the release of glucose.
  • Glucose raises your blood sugar.
  • The stress hormones keep your blood sugar high by making your cells insulin resistant. (This is one reason that morning hyperglycemia can be hard to treat when it happens.)


The primary symptom of the Somogyi effect versus other causes is hypoglycemia at 2 to 3 am. Others include:

  • rapid heart rate
  • night sweats
  • waking up with a headache
  • confusion and/or dizziness
  • blurred vision
  • increased appetite/thirst


See your doctor. You need your medical team for this.


The Somogyi effect isn’t a roadblock on the journey through diabetes. It’s a perfectly treatable speedbump – if you bring your doctor along for the ride.