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Understanding the Dawn & Somogyi Effects in Diabetes

Diabetics sometimes measure high blood sugar levels in the morning before eating, even though they may have had normal levels before retiring. This can be puzzling, since the high glucose reading may be taken more than eight or nine hours since any food was eaten. There are two common explanations for this apparent incongruity: the dawn phenomenon and the Somogyi effect. Both involve the reaction of the body to nighttime changes in our blood chemistry.

  1. The Dawn Phenomenon

    • Sleep brings release of hormones that may block the effectiveness of insulin

      The dawn pPhenomenon is a response to changes in the body's blood chemistry brought about by hormone release. When a healthy individual is asleep, growth hormone and two adrenal hormones (catecholamines and cortisol) are released into the blood stream. This happens in the early morning hours, and the hormones can sometimes block the effectiveness of insulin. A diabetic who does not produce enough insulin to counteract this hormonal effect will see a pre-breakfast rise in her blood sugar.

    The Somogyi Effect

    • The Somogyi effect is sometimes called "rebound hyperglycemia" which is descriptive of exactly what happens. While sleeping, some people's blood sugar may drop below a value of 70 milligrams/deciliter (mg/dl), a condition called hypoglycemia. When this happens, the body signals for the release of stored glucose that causes the blood sugar to rise. It can sometimes rise too much, resulting in high blood sugar or hyperglycemia. Individuals taking insulin or diabetes pills are more susceptible to this rebound hyperglycemia.

    Determining Which It Is

    • Checking between 2 and 3 a.m. may show the Somogyi effect.

      Since the symptoms are similar, knowing which is the cause of an individual's fasting high blood sugar requires some investigation. Luckily there is an easily found tell-tale clue for the Somogyi effect: it causes the blood sugar levels to fall between 2 and 3 a.m. You can set your alarm for that hour of the morning and test your blood sugar. If it's low, the Somogyi effect is the likely cause of the problem. If it's high or normal, then the dawn phenomenon is more likely the culprit.

    Treating the Dawn Phenomenon

    • Check with your physician to treat the dawn phenomenon. There may be a medication or an insulin adjustment called for. Exercising later in the day may cause blood-sugar levels to be lower during the night. Toward the same end, eat a protein-rich bedtime snack such as meat, cheese, or peanut butter instead of carbohydrates. Eat an early breakfast. Eating tells your body to turn off the hormones that caused the problem. In this case, eating can help your blood sugar level to drop.

    Treating the Somogyi Effect

    • Never change your medication or dosage without your doctor's advice

      Check with your physician to treat the Somogyi effect. Ask if a three-day Continuous Glucose Monitoring System test is in order (CGMS). The test employs a small device that continuously monitors blood glucose levels by way of a small tube inserted under the skin. It will show exactly when low blood sugar levels occur. Just as with the dawn phenomenon, have a protein snack before bed. Never change your medication or dosage without your doctor's advice.

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