Diabetes is a condition in which the levels of blood sugar, or glucose, are not properly regulated. It is related to a hormone called insulin, which controls glucose levels.
In one type of diabetes, the body does not produce enough insulin. This is the case in juvenile-onset diabetes, or diabetes that develops before adulthood. In another form of diabetes, the insulin that is produced is not used effectively by the body. This is the case in both diabetes that develops during pregnancy and in adult-onset diabetes (diabetes that develops during adulthood).
Diabetes that develops during pregnancy in a woman who did not have the condition before pregnancy is called gestational diabetes. Gestational diabetes is thought to result from metabolic changes brought about by the effects of hormones in pregnancy. About 1 to 5 percent of women whose glucose levels are tested during pregnancy are found to have gestational diabetes. Women with gestational diabetes usually do not have glucose levels that are high enough to pose risks to their own health. In most cases, gestational diabetes causes no symptoms in the mother and poses no immediate threat to her health. Even so, it is an early warning sign that she has a greater risk of developing diabetes later in her life.
Although gestational diabetes is usually not a threat to the mother's health, doctors test for it because it poses some real risks for the baby. If gestational diabetes goes undetected, the baby has an increased risk of stillbirth or death as a newborn. But when the problem is properly diagnosed and managed, your baby is at no greater risk than a baby whose mother does not have diabetes.
The major risk for babies of women with gestational diabetes is macrosomia, or excessive weight at birth. Most doctors define macrosomia as a birth weight of 4,500 grams (9 pounds 14 ounces) or more. A baby as large as this may have difficulty being born. Both the likelihood of cesarean birth and the risk of birth injuries are increased when the baby is macrosomic. Keeping the glucose level of a mother who has gestational diabetes within the normal range is thought to decrease this risk.
Other problems that may develop as a result of gestational diabetes include hypoglycemia, or low blood sugar, in the baby shortly after birth. This may occur because the baby has been accustomed to receiving high levels of blood sugar across the placenta, and the supply is abruptly stopped when the umbilical cord is cut at birth. Babies born to mothers with diabetes should have their glucose levels checked regularly after delivery. They frequently need early feeding or, occasionally, a glucose solution through an intravenous line to prevent low blood sugar.
If you have been diagnosed with gestational diabetes, you may be concerned about the possibility of your baby developing diabetes as an older child. Fortunately, there is no increased risk of juvenile-onset diabetes in babies born to mothers with gestational diabetes. Risk factors for diabetes in pregnancy include age older than 30, a family history of adult-onset diabetes, a previous large baby, a previous stillborn baby, and obesity. But nearly half of women with gestational diabetes have no risk factors. Because heredity plays a major role in the development of gestational diabetes, there is nothing a pregnant woman can do to avoid or cause it. If you have gestational diabetes, there is no need to feel guilty, or to worry about whether it was caused by something you did or didn't do. Although a balanced diet is important during your pregnancy, you cannot make yourself diabetic by gaining too much weight or by eating too much sugar.
What are the symptoms? Generally, gestational diabetes does not cause any symptoms. Subtle signs, such as fatigue or excessive thirst and urination, may sometimes occur, but many women without gestational diabetes also experience these changes late in pregnancy. Because the condition cannot be diagnosed on the basis of the mother's symptoms, glucose testing must be done to detect it.
Gestational diabetes is detected through glucose tolerance testing. This test is generally performed at 26 to 28 weeks of pregnancy, but it may be performed earlier if your doctor feels you are at high risk for developing this condition. Because about half of women who develop diabetes during pregnancy have no risk factors for the condition, many doctors, though not all, choose to check all women for gestational diabetes, regardless of their age or risk factors.
The key to managing gestational diabetes is controlling your blood sugar level. In most cases, this can be done through a carefully planned diet, plenty of exercise, and regular testing of the blood glucose level. Once gestational diabetes is diagnosed, many doctors will obtain a set of glucose test results each week until you deliver. The set consists of testing your glucose levels in the morning before you have eaten breakfast and again two hours after you have eaten breakfast. Some doctors also include a mid-afternoon blood sugar level in the set.
To keep track of how well you are controlling your diabetes, your doctor may recommend that you use a home testing kit to check your blood glucose more often than once a week. Test strips for testing sugar in the urine are not useful for monitoring glucose levels in pregnancy because there is little correlation between the sugar levels in the blood and in the urine.
In almost all women with gestational diabetes, the condition can be controlled through diet and careful monitoring of glucose level. If, despite diet and exercise, a woman's blood glucose level remains too high, daily insulin injections may be required to lower it to a safe level. Insulin does not cross the placenta to reach the baby. Medication taken by mouth to lower the blood glucose level is not given during pregnancy.
In addition to helping you maintain a normal blood glucose level, your doctor may also advise weekly monitoring of the baby during the last weeks of pregnancy. This may be done by non-stress testing, contraction stress testing, or biophysical profiles. An ultrasound exam may also be done to measure the size and weight of the baby in the last weeks before your due date. This test can help your doctor decide whether a cesarean birth will be needed. She or he may also ask you to keep a "kick count," a record of how often you feel your baby moving.
Because of the higher likelihood of large babies in mothers who have diabetes, cesarean birth is more common. The need for a cesarean birth is difficult to predict before labor, however, unless the baby is very large or the mother's pelvis is very small. Most often, a cesarean procedure becomes necessary because of "failure to progress" in labor. This happens when the cervix stops dilating or the baby does not descend in the birth canal. The risk of birth injuries due to an overly large infant is also increased in pregnancies complicated by gestational diabetes.
In most women with gestational diabetes, the baby usually does not have to be delivered before term. If labor has not begun on its own by 40 to 41 weeks, it may be induced with oxytocin. Amniocentesis might be performed beforehand to determine whether the baby's lungs are mature enough for delivery.
Gestational diabetes almost always disappears shortly after delivery. To make sure that your glucose level has returned to normal, your doctor may check it once or twice on the day after delivery. The glucose test may be repeated six weeks after delivery.
If you have had gestational diabetes in one pregnancy, your risk of it developing again in another pregnancy is increased. You are also more likely to develop "overt" diabetes (diabetes that is present all the time, not just during pregnancy) as you get older. About half of women with gestational diabetes eventually develop overt diabetes. For this reason, it is important to follow your doctor's advice concerning diet and exercise after delivery and to have your glucose level checked at least yearly. Women who develop diabetes in pregnancy can breast feed their babies and are encouraged to do so.