Diabetics testing their blood sugar on waking are sometimes surprised to find them higher than when they went to bed. How is it possible that, even without eating anything, the glucose level in your blood has gone up during the night?
There are three main reasons why this can occur in diabetics and for proper blood sugar control, we need to understand them.
This is the name for the process in which the liver converts amino acids into glucose. We are usually taught that glucose comes from carbohydrates but the body is also able to metabolise proteins to liberate some glucose as well.
Whereas insulin is the hormone that enables muscles and fat tissue to absorb glucose from the blood stream, this lowering blood glucose, there is also a hormone called glucagon which acts on the liver to liberate more glucose.
The two hormones work in tandem to maintain a correct balance. Some diabetics produce enough insulin to prevent the action of glucagon causing the release of more glucose from the liver. But where the level of insulin falls below a certain level, it is possible for the liver to inappropriately respond to glucagon and dump glucose into the blood stream.
This effect normally has to be controlled with drugs.
The Dawn Phenomenon
Although this area is not yet very well researched, it seems that the liver can deactivate more circulating insulin in the early hours of the morning.
As a result, the balance between insulin and glucagon is disturbed and the glucagon acts on the liver to cause gluconeogenesis, the release of glucose from the liver, which raises the blood sugar level.
So even doing nothing at all, eating nothing during the night, the liver can produce extra glucose which raises the blood sugar level seen on waking. The rise takes place a little before waking but unfortunately it cannot be avoided by waking a little earlier.
This means the delayed passage of food through the gut and the cause seems to be damage to the nerves which control the stomach and the gut, affecting how long it takes for food to pass through.
Because the passage of food is delayed, so too is the release of the nutrients including the glucose generated from the carbohydrates and proteins.
There is some evidence that long-term elevated blood glucose can lead to this type of nerve damage. Although the blood glucose level may seem reasonable before going to bed, the gut will digest the food during the night causing elevated levels on waking.
Gastroparesis is particularly important for those diabetics who are managing their sugar levels with injections of insulin as it affects the appropriate dosage.
Gluconeogenesis and the dawn phenomenon seem to be more controlable by using a low carb diet in conjunction with drugs but gastroparesis seems to be more complex. The latter particularly is a concern for those injecting insulin and requires very careful monitoring together with treatment for the slow stomach-emptying.
Understanding high waking sugar levels helps diabetics to better control their diet and to establish better management of their diabetes.