Gestational diabetes is a condition in which the glucose level is
elevated and other diabetic symptoms appear during pregnancy, in a woman
who has not previously been diagnosed with diabetes. All diabetic symptoms
disappear following delivery. Unlike type 1 diabetes, gestational diabetes
is not caused by a lack of insulin, but by blocking effects of other
hormones on the insulin that is produced, a condition referred to as
'insulin resistance'.
What causes gestational diabetes?
Although the cause of gestational diabetes is not
known, there are some theories as to why the condition occurs.
The placenta supplies a growing fetus with nutrients and water, as well
as produces a variety of hormones to maintain the pregnancy. Some of these
hormones (estrogen, cortisol, and human placental lactogen) can have a blocking
effect on insulin. This is called 'contra-insulin effect', which usually
begins about 20 to 24 weeks into the pregnancy. As the placenta grows, more
of these hormones are produced, and insulin resistance becomes greater.
Normally, the pancreas is able to make additional insulin to overcome insulin
resistance, but when the production of insulin is not enough to overcome
the effect of the placental hormones, gestational diabetes results.
What are the risks factors associated with gestational
diabetes?
Although any woman might develop gestational diabetes during pregnancy,
some of the factors that may increase risk are:
Obesity · family history of diabetes
Having given birth previously to a very large infant, a still birth,
or a child with a birth defect
Having too much amniotic fluid (polyhydramnios)
Women who are older than 25 are at greater risk than younger women
Although increased glucose in the urine is often included in the list
of risk factors, it is not believed to be a reliable indicator for gestational
diabetes.
How is gestational diabetes diagnosed?
Gestational diabetes is diagnosed by a glucose-screening
test, which involves drinking a glucose drink followed by measurement of
glucose levels after a one-hour interval. If this test shows a blood sugar
level of greater than 140 mg/dl, another test will be performed after a
few days of following a special diet.
The second test also involves drinking a glucose drink, and results are
measured at three-hour intervals. If results of the second test are in the
abnormal range, gestational diabetes is diagnosed.
What is the treatment for gestational diabetes?
Treatment for gestational diabetes is by keeping blood glucose levels
in the normal range. All treatments will depend on a person's age, overall
health, and medical history. Treatment may include:
special diet
exercise
daily blood glucose monitoring
insulin injections
Possible complications for the baby:
Unlike type 1 diabetes, gestational diabetes generally does not cause
birth defects. Birth defects usually originate sometime during the first
trimester (before the 13th week) of pregnancy. But, the insulin resistance
from the contra-insulin hormones produced by the placenta does not usually
occur until approximately the 24th week. Women with gestational diabetes
generally have normal blood sugar levels during the critical first trimester.
The complications of gestational diabetes are usually manageable and preventable.
The key to prevention is careful control of blood sugar levels as soon
as the diagnosis of gestational diabetes is made.
Infants of mothers with gestational diabetes are vulnerable to several
chemical imbalances, such as low serum calcium and low serum magnesium
levels, but in general, there are two major problems of gestational diabetes:
macrosomia and hypoglycemia. Macrosomia - refers to a baby that is considerably
larger than normal. All of the nutrients the fetus receives come directly
from the mother's blood. If the maternal blood has too much glucose, the
pancreas of the fetus senses the high glucose levels and produces more
insulin in an attempt to use this glucose. The fetus converts the extra
glucose to fat. Even when the mother has gestational diabetes, the fetus
is able to produce all the insulin it needs. The combination of high blood
glucose levels from the mother and high insulin levels in the fetus results
in large deposits of fat, which causes the fetus to grow excessively large.
Hypoglycemia - refers to low blood sugar in the baby immediately
after delivery. This problem occurs if the mother's blood sugar levels
have been consistently high causing the fetus to have a high level of
insulin in its circulation. After delivery, the baby continues to have
a high insulin level, but it no longer has the high level of sugar from
its mother, resulting in the newborn's blood sugar level becoming very
low. The baby's blood sugar level is checked after birth, and if the level
is too low, it may be necessary to give the baby glucose intravenously.
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