Dawn Phenomenon.

While it has rather an attractive name the Dawn Phenomenon can cause problems for diabetic's.

When fasting blood sugar levels in the morning are much higher than the pre-bedtime reading, with no food eaten in between there is obviously a problem somewhere.

So What is the Dawn Phenomenon?

The Dawn Phenomenon occurs when there is an apparently unexplained morning rise in the fasting blood sugar (blood glucose) levels. That is when the fasting (pre-breakfast) level in the morning is higher than the pre bed-time level.

Increased morning blood sugar levels can have two causes -

  1. The Liver dumps its reserve of glycogen (a form of glucose) when blood sugar levels get too low.

  2. Insufficient Insulin in the blood together with increased Insulin Resistance due to hormones released in the early morning.

The hormonal changes are basically preparing the body for the expected exertions of the morning and occur in everyone, both diabetic and non-diabetic. In diabetic's though they can raise blood sugar levels to high and cause further difficulties at breakfast time.

How to Prevent or Lessen the Effect of the Dawn Phenomenon

The two causes have two different solutions and you need to find out which is occurring first.

Check blood sugar (glucose) levels at 2-3am, if they are regularly very low followed by a higher bounce in the morning fasting level, its likely to be a liver dump.

Otherwise if the blood sugar levels are more or less the same as it bed-time followed by a rise in the morning fasting level its likely to be insufficient insulin that may be combined with early morning insulin resistance.

Dawn Phenomenon an apparently unexplained rise in fasting blood sugar levels

Liver Dumps

Liver dumps cause a sudden release of glucose in the blood leading to a quick increase in blood sugar levels. They may happen after a blood sugar low or hypo that may wake you in the early morning.

A small snack last thing at night can help; a mix of carbohydrate, fibre, protein & fat to slow the release of blood sugar. Something like Cheese on Toast, Peanut Butter on Ryvita and so on.

Insufficient Insulin

For diabetic's injecting insulin a common cause of high fasting blood sugar levels in the morning, can be if the insulin runs low during the night. That combined with a lessened effect of any remaining insulin due to hormonal changes that occur in the early morning.

The remaining insulin is insufficient to cover the background needs of the body even at sleep. So after about 4am, blood sugar levels gradually rise.

For Type 2's on drugs this is likely to be a lesser effect because their pancreas still has some remaining insulin production.

Morning Insulin Resistance

Insulin Resistance may remain high for many hours including before and after breakfast. Carbohydrates eaten in the morning may cause a greater increase in blood sugar levels than carbohydrates eaten at mid-day or evening.