The Dawn Phenomenon
Have you experience the Dawn phenomenon? You went to bed the perfect 100 mg/dl and wake-up in the morning on a high. Well, I wish it was that sort of a high but its high blood glucose levels. But what is it, really? Dawn phenomenon is represented by very high morning blood glucose levels due to the release of certain hormones in the middle of the night. Everybody experiences this physiological phenomenon, but it can be troublesome for people with diabetes. The body makes certain hormones called counterregulatory hormones, which work against the action of insulin. The counterregulatory hormones include: • Glucagon• Growth hormone• Cortisol • Catecholamines• Epinephrine (adrenaline) How do these hormones cause high blood glucose levels? These hormones raise blood glucose levels by signalling the liver to release more glucose from stored glycogen and also inhibit glucose utilization within the body’s cells and muscle tissues by suppressing the activity of insulin. As a result the glucose levels continue to rise to abnormal levels. Why does this happen? It is thought that this process was meant to give the body the energy it needs to wake up in the morning to go hunting for food. In nondiabetic people, the body responds to the excess glucose by producing insulin. The insulin then moves the excess glucose into the cells and muscle tissues returning blood glucose levels to within normal range. How does this phenomenon affect diabetics? In people with Type 1 diabetes (whose pancreases don’t make insulin) and Type 2 diabetes (whose livers may not respond well enough to insulin to stop the excess glucose production) glucose levels will continue to rise above normal levels causing hyperglycemia. The blood glucose level rises normally occurs between 3am and 8am but sometimes it may continue to rise until much later in the morning. The dawn phenomenon is not always at fault for morning rise in blood glucose levels. In some instances high blood glucose levels in the morning may be as a result of environmental factors over which you have control. Other factors If during sleep you experience low blood glucose levels because of the lack of food overnight the body may produce a “rebound effect” to compensate. This rebound response causes the liver to produce abnormally high levels of glucose. Let’s just say it is the body’s defence mechanism to protect itself from hypoglycemia. This high level of glucose production is actually known as rebound hyperglycemia, or Somogyi effect. How can I be certain of the exact cause of my high blood glucose level? The only way to tell the two phenomena apart is to check your blood glucose level at around 4 a.m. in the morning and compare it to your waking glucose level. If your blood glucose level is very high in both reading you may be experiencing the dawn phenomenon. If your blood sugar is low in the first reading and high in the second you may be experiencing the rebound hyperglycemia or the Somogyi effect.
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