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Dawn Phenomenon and the Somogyi Effect

Dawn Phenomenon (feh-NAH-meh-nun): Rise in blood glucose level in the early-morning (4 a.m. to 8 a.m.)

Somogyi (suh-MOH-jee) Effect, also called rebound hyperglycemia: When the blood glucose level swings high following hypoglycemia. The Somogyi effect may follow an untreated hypoglycemic episode during the night and is caused by the release of stress hormones.


Everyone, diabetic or not, exhibits some Dawn Phenomenon. It is a natural part of our bodies. The Dawn Phenomenon is the reason most diabetics are far more sensitive to carbs in the morning.

Since most of us fast while sleeping, our bodies use stored energy during sleep. The body uses all three macro-nutrients (carbohydrates, proteins, and fats) to store energy.

Carbohydrates: Glycogen is made from glucose, and is stored in the liver and muscles. Since it is basically nothing more than a complex matrix of glucose, it is easy for the body to store and use, something the body does all day long. The technical term for the act of creating and storing glycogen is glycogenesis. When the body calls for the conversion of glycogen back to glucose it is called glycogenolysis.

Protein: Most of us think of our protein as being stored in muscle, but the body has protective mechanisms to make muscle wasting its last choice. One of the most useful and readily available sources of protein storage is in blood components, i.e., albumin (plasma). The body uses a process performed in the liver to convert amino acids, the building blocks of proteins, into glucose. The name for this process is gluconeogenesis, literally "the creation of new glucose."

Overnight, usually between 4am and 11am, our body releases some hormones. These are Growth Hormone (GH) from the anterior pituitary gland, cortisol from the adrenal cortex, glucagon from your pancreatic alpha-cells, and epinephrine (adrenalin). These hormones cause an increase in insulin resistance, raising our BG. In addition, these hormones trigger glycogenolysis and gluconeogenesis, adding stored or new glucose to our bloodstream.

If you are experiencing the Dawn Phenomenon, and you are diabetic, check what solutions below work for you.

  • Try eating no food after dinner. This works for people whose Dawn Phenomenon isn't very strong. Basically, it lowers their baseline BG, so that when DP does hit them, the increase keeps them below a certain level, usually 120 (6.7).
  • Try eating a small snack of fat and protein before bed. Most find that a tablespoon of peanut butter, or some cheese and deli meat are effective. The theory here is that the slow-digesting fat and protein holds their BG high enough overnight to avoid Somogyi Effect.
  • Learn how the two disparate approaches above work for you. Hopefully, you will set personal targets to guide you, for example, if my BG is below XXX (insert your target here), I need a snack. If my BG is over XXX, I don't need a snack.
  • The prescription medication Metformin HCl (Glucophage) is often very effective in limiting Dawn Phenomenon for Type-2s and insulin resistant Type-1s. Of course, Type-1s can adjust their basal (slow) insulin regimen to account for Dawn Phenomenon.
  • Eat breakfast. The resulting increase in blood glucose from food will often turn off the continued rise.


Somogyi Effect, is a high morning BG due to a low overnight. It is most commonly seen with diabetics that use insulin, but is also seen with overnight reactive hypoglycemics. Setting your bedtime BG target a bit higher will usually prevent you from having a hypoglycemic event overnight.

The mechanism is a low overnight, which causes the body to react by releasing many of the same hormones seen in Dawn Phenomenon. The strongest blood glucose increasing hormone, glucagon, plays an important role. It tells your liver to start glycogenolysis and gluconeogenesis to provide enough glucose for your body to survive. Often, this mechanism over-produces, and you wake to a significantly higher BG.

Source: Diabetic-Talk Organization

Adapted by Editorial Staff, April 2007. Last update, August 2008



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