There are two reasons why your blood sugars
levels may be high in the morning - the dawn phenomenon and
the Somogyi effect.
Dawn phenomenon. The
dawn phenomenon is the end result of a combination of natural body
changes that occur during the sleep cycle and can be explained as
follows. Your body has little need for insulin between about
midnight and about 3:00 a.m. (a time when your body is sleeping
most soundly). Any insulin taken in the evening causes blood sugar
levels to drop sharply during this time. Then, between 3:00 a.m.
and 8:00 a.m., your body starts churning out stored glucose (sugar)
to prepare for the upcoming day as well as releases hormones that
reduce the body's sensitivity to insulin. All of these events
happen as your bedtime insulin dose is also wearing off. These
events, taken together, cause your body's blood sugar levels
to rise in the morning (at "dawn").
Somogyi effect. A
second cause of high blood sugar levels in the morning might be due
to the Somogyi effect (named after the doctor who first wrote about
it). This condition is also called "rebound hyperglycemia."
Although the cascade of events and end result - high blood
sugar levels in the morning - is the same as in the dawn
phenomenon, the cause is more "man-made" (a result of poor
diabetes management) in the Somogyi effect. There are two potential
causes. In one scenario, your blood sugar may drop too low in the
middle of the night and then your body releases hormones to raise
the sugar levels. This could happen if you took too much insulin
earlier or if you did not have enough of a bedtime snack. The other
scenario is when your dose of long-acting insulin at bedtime is not
enough and you wake up with a high morning blood sugar.
Because the cascade of events is the same with
both scenarios, how is it determined if the dawn phenomenon or
Somogyi effect is causing the high blood sugar
levels?
Your doctor will likely ask
you to check your blood sugar levels between 2:00 a.m. and 3:00
a.m. for several nights in a row. If your blood sugar is
consistently low during this time, the Somogyi effect is suspected.
If the blood sugar is normal or high during this time period, the
dawn phenomenon is more likely to be the cause.
How can this situation be
corrected?
Once you and your doctor
determine how your blood sugar levels are behaving at night, he or
she can advise you about the changes you need to make to better
control them. Options that your doctor may discuss
include:
- Changing the time you take the long-acting
insulin in the evening so that its peak action occurs when your
blood sugars start rising
- Changing the type of insulin you take in the
evening
- Taking extra insulin overnight
- Eating a lighter breakfast
- Increasing your morning dose of
insulin
- Switching to an insulin pump, which can be
programmed to release additional insulin in the morning