Understanding Gestational Diabetes: Glucose Monitoring

What is self blood glucose monitoring?
Once you are diagnosed as having gestational diabetes, you and your health care providers will want to know more about your day-to-day blood sugar levels. It is important to know how your exercise habits and eating patterns affect your blood sugars. Also, as your pregnancy progresses, the placenta will release more of the hormones that work against insulin. Testing your blood sugar level at important times during the day will help determine if proper diet and weight gain have kept blood sugar levels normal or if extra insulin is needed to help keep the fetus protected.

Self blood glucose monitoring is done by using a special device to obtain a drop of your blood and test it for your blood sugar level. Your doctor or other health care provider will explain the procedure to you. Make sure that you are shown how to do the testing before attempting it on your own. Some items you may use to monitor your blood sugar levels are:

Lancet–a disposable, sharp needle-like sticker for pricking the finger to obtain a drop of blood.
Lancet device–a spring­loaded finger sticking device.
Test strip–a chemically treated strip to which a drop of blood is applied.
Color chart–a chart used to compare against the color on the test strip for blood sugar level.
Glucose meter–a device which “reads” the test strip and gives you a digital number value.

Your health care provider can advise you where to obtain the self-monitoring equipment in your area. You may want to inquire if any places rent or loan glucose meters, since it is likely you won't be needing it after your baby is born.

How often and when should I test?
You may need to test your blood several times a day. Generally, these times are fasting (first thing in the morning before you eat) and 2 hours after each meal. Occasionally, you may be asked to test more frequently during the day or at night. As each person is an individual, your health care provider can advise the schedule best for you.

How should I record my test results?
Most manufacturers of glucose testing products provide a record diary, although some health care providers may have their own version. A Self Blood Glucose Monitoring Diary is included at the end of this book.

You should record any test result immediately because it's easy to forget what the reading was during the course of a busy day. You should always have this diary with you when you visit your doctor or other health care provider or when you contact them by phone. These results are very important in making decisions about your health care.

Are there any other tests I should know about?
In addition to blood testing, you may be asked to check your urine for ketones. Ketones are by-products of the breakdown of fat and may be found in the blood and urine as a result of inadequate insulin or from inadequate calories in your diet. Although it is not known whether or not small amounts of ketones can harm the fetus, when large amounts of ketones are present they are accompanied by a blood condition, acidosis, which is known to harm the fetus. To be on the safe side, you should watch for them in your urine and report any positive results to your doctor.

How do I test for ketones?
To test the urine for ketones, you can use a test strip similar to the one used for testing your blood. This test strip has a special chemically treated pad to detect ketones in the urine. Testing is done by passing the test strip through the stream of urine or dipping the strip in and out of urine in a container. As your pregnancy progresses, you might find it easier to use the container method. All test strips are disposable and can be used only once. This applies to blood sugar test strips also. You cannot use your blood sugar test strips for urine testing, and you cannot use your urine ketone test strips for blood sugar testing.

When do I test for ketones?
Overnight is the longest fasting period, so you should test your urine first thing in the morning every day and any time your blood sugar level goes over 240 mg/dl on the blood glucose test. It is also important to test if you become ill and are eating less food than normal. Your health care provider can advise what's best for you.

Is it ever necessary to take insulin?
Yes, despite careful attention to diet some women's blood sugars do not stay within an acceptable range. A pregnant woman free of gestational diabetes rarely has a blood glucose level that exceeds 100 mg/dl in the morning before breakfast (fasting) or 2 hours after a meal. The optimum goal for a gestational diabetic is blood sugar levels that are the same as those of a woman without diabetes.

There is no absolute blood sugar level that necessitates beginning insulin injections. However, many physicians begin insulin if the fasting sugar exceeds 105 mg/dl or if the level 2 hours after a meal exceeds 120 mg/dl on two separate occasions. Blood sugar levels measured by you at home will help your doctor know when it is necessary to begin insulin. The ability to perform self blood glucose monitoring has made it possible to begin insulin therapy at the earliest sign of high sugar levels, thereby preventing the fetus from being exposed to high levels of glucose from the mother's blood.

Will my baby be healthy?
The ultimate concern of any expectant mother is, “Will my baby be all right?” There is an array of simple, safe tests used to assess the condition of the fetus before birth and these can be particularly valuable during a pregnancy complicated by gestational diabetes. Tests that may be given during your pregnancy include:

Ultrasound.
Ultrasound uses short pulses of high­frequency, low­intensity sound waves to create images. Unlike x-rays, there is no radiation exposure to the fetus. First used during World War II to detect enemy submarines below the surface of the water, ultrasound has since been used safely in obstetrics. Occasionally, the date of your last menstrual period is not sufficient to determine a due date. Ultrasound can provide an accurate gestational age and due date that may be very important if it is necessary to induce labor early or perform a cesarean delivery. Ultrasound can also be used to determine the position of the placenta if it is necessary to perform an amniocentesis (another test discussed later).

Fetal movement records.
Recording fetal movement is a test you can do by yourself to help determine the condition of the baby. Fetal activity is generally a reassuring sign of well-being. Women are often asked to count fetal movements regularly during the last trimester of pregnancy. You may be asked to set aside specific times to lie down on your back or side and count the number of times the baby moves or kicks. Three or more movements in a 2-hour period is considered normal. Contact your obstetrician if you feel fewer than three movements to determine if other tests are needed.

Fetal monitoring.
Modern instruments make it possible to monitor the baby's heart rate before delivery. Currently, there are two types of fetal monitors - internal and external. The internal monitor consists of a small wire electrode attached directly to the scalp of the fetus after the membranes have ruptured. The external monitor uses transducers secured to the mother's abdomen by an elastic belt. One transducer records the baby's heart rate by a sensitive microphone called a doppler. The other transducer measures the firmness of the abdomen during a contraction of the uterus. It is a crude measure of the strength and frequency of contractions. Fetal monitoring is the basis for the non-stress test and the oxytocin challenge test described below.

Non-stress test.
The “non­stress” test refers to the fact that no medication is given to the mother to cause movement of the fetus or contraction of the uterus. It is often used to confirm the well-being of the fetus based on the principle that a healthy fetus will demonstrate an acceleration in its heart rate following movement. Fetal activity may be spontaneous or induced by external manipulation such as rubbing the mother's abdomen or making a loud noise above the abdomen with a special device. When movement of the fetus is noted, a recording of the fetal heart rate is made. If the heart rate goes up, the test is normal. If the heart rate does not accelerate, the fetus may merely be “sleeping”; if, after stimulation, the fetus still does not react, it may be necessary to perform a “stress test” (oxytocin challenge test).

Stress test (oxytocin challenge test).
Labor represents a stress to the fetus. Every time the uterus contracts, the fetus is momentarily deprived of its usual blood supply and oxygen. This is not a problem for most babies. However, some babies are not healthy enough to handle the stress and demonstrate an abnormal heart rate pattern. This test is often done if the non-stress test is abnormal. It involves giving the hormone oxytocin (secreted by every mother when normal labor begins) to the mother to stimulate uterine contractions. The contractions are a challenge to the baby, similar to the challenge of normal labor. If the baby's heart rate slows down rather than speeds up after a contraction, the baby may be in jeopardy. The stress test is considered more accurate than the non­stress test. Nevertheless, it is not 100 percent fool­proof and your obstetrician may want to repeat it on another occasion to ensure its accuracy. Most women describe this test as mildly uncomfortable but not painful.

Amniocentesis.
Amniocentesis is a method of removing a small amount of fluid from the amniotic sac for analysis. Either the fluid itself or the cells shed by the fetus into the fluid can be studied. In mid­pregnancy the cells in amniotic fluid can be analyzed for genetic abnormalities such as Down syndrome. Many women over the age of 35 have amniocentesis for just this reason. Another important use for amniocentesis late in pregnancy is to study the fluid itself to determine if the lungs of the fetus are mature and able to withstand early delivery This information can be very important in deciding the best time for a woman with Type I diabetes to deliver. It is not done as frequently to women with gestational diabetes.

Amniocentesis can be performed in an obstetrician's office or on an outpatient basis in a hospital. For genetic testing, amniocentesis is usually performed around the 16th week when the placenta and fetus can be located easily with ultrasound and a needle can be inserted safely into the amniotic sac. The overall complication rate for amniocentesis is less than 1 percent. The risk is even lower during the third trimester when the amniotic sac is larger and easily identifiable.

Does gestational diabetes affect labor and delivery?
Most women with gestational diabetes can complete pregnancy and begin labor naturally. Any pregnant woman has a slight chance (about 5 percent) of developing preclampsia (toxemia), a sudden onset of high blood pressure associated with protein in the urine, occurring late in pregnancy. If preclampsia develops, your obstetrician may recommend an early delivery. When an early delivery is anticipated, an amniocentesis is usually performed to assess the maturity of the baby's lungs.

Gestational diabetes, by itself, is not an indication to perform a cesarean delivery, but sometimes there are other reasons your doctor may elect to do a cesarean. For example, the baby may be too large (macrosomic) to deliver vaginally, or the baby may be in distress and unable to withstand vaginal delivery. You should discuss the various possibilities for delivery with your obstetrician so there are no surprises.

Careful control of blood sugar levels remains important even during labor. If a mother's blood sugar level becomes elevated during labor, the baby's blood sugar level will also become elevated. High blood sugars in the mother produce high insulin levels in the baby. Immediately after delivery high insulin levels in the baby can drive its blood sugar level very low since it will no longer have the high sugar concentration from its mother's blood.

Women whose gestational diabetes does not require that they take insulin during their pregnancy, will not need to take insulin during their labor or delivery. On the other hand, a woman who does require insulin during pregnancy may be given insulin by injection on the morning labor begins, or in some instances, it may be given intravenously throughout labor. For most women with gestational diabetes there is no need for insulin after the baby is born and blood sugar level returns to normal immediately. The reason for this sudden return to normal lies in the fact that when the placenta is removed the hormones it was producing (which caused the insulin resistance) are also removed. Thus, the mother's insulin is permitted to work normally without resistance. Your doctor may want to check your blood sugar level the next morning, but it will most likely be normal.

Should I expect my baby to have any problems?
One of the most frequently asked questions is, “Will my baby have diabetes?” Almost universally the answer is no. However, the baby is at risk for developing Type II diabetes later in life, and of having other problems related to gestational diabetes, such as hypoglycemia (low blood sugar) mentioned earlier. If your blood sugars were not elevated during the 24 hours before delivery, there is a good chance that hypoglycemia will not be a problem for your baby. Nevertheless, a neonatologist (a doctor who specializes in the care of newborn infants) or other doctor should check your baby's blood sugar level and give extra glucose if necessary.

Another problem that may develop in the infant of a mother with gestational diabetes is jaundice. Jaundice occurs when extra red blood cells in the baby's circulation are destroyed, releasing a substance called bilirubin. Bilirubin is a pigment that causes a yellow discoloration of the skin (jaundice). A minor degree of jaundice is common in many newborns. However, the presence of large amounts of bilirubin in the baby's system can be harmful and requires placing the baby under special lights which help get rid of the pigment. In extreme cases, blood transfusions may be necessary.
Will I develop diabetes in the future?
For most women gestational diabetes disappears immediately after delivery. However, you should have your blood sugars checked after your baby is born to make sure your levels have returned to normal. Women who had gestational diabetes during one pregnancy are at greater risk of developing it in a subsequent pregnancy. It is important that you have appropriate screening tests for gestational diabetes during future pregnancies as early as the first trimester.

Pregnancy is a kind of “stress test” that often predicts future diabetic problems. In one large study more than one­half of all women who had gestational diabetes developed overt Type II diabetes within 15 years of pregnancy. Because of the risk of developing Type II diabetes in the future, you should have your blood sugar level checked when you see your doctor for your routine check­ups. There is a good chance you will be able to reduce the risk of developing diabetes later in life by maintaining an ideal body weight and exercising regularly.