Gestational Diabetes Testing
Gestational Diabetes Testing What is Gestational Diabetes (or “GDM”)?
Gestational Diabetes (GDM) is diabetes that develops during pregnancy. Like other types of diabetes, gestational diabetes affects how your cells use sugar or glucose. The placenta produces hormones that support your baby’s growth and development. These same hormones make it more difficult for you to process sugar normally. Gestational diabetes starts when your body can no longer process the sugar, and the sugar (glucose) builds up in your blood. High blood sugar levels (hyperglycemia) can have damaging effects on you and your baby. Generally, there are no symptoms at all. Anyone (about 7 to 10% of all pregnant women) can develop GDM, even if you have no risk factors. There are, however, some factors that increase your risk of developing GDM:
● Being over the age of 25
● Having a close relative with diabetes
● Being Overweight (especially if your BMI is 30 or higher)
● Excessive weight gain during pregnancy
● PCOS (polycystic ovarian syndrome)
● Have had GDM before
● Have had a big baby (over 9 pounds) before
● Certain medications (glucocorticoids for asthma or autoimmune disorders); beta-
● blockers (for high blood pressure or rapid heart rate); antipsychotic medication (for
● mental health problems)
● > Certain ethnic groups (African American, Native American, Asian, Hispanic, or Pacific
How can Gestational Diabetes (GDM) affect me, my pregnancy and my baby?
Gestational Diabetes greatly increases the risks for:
● High blood pressure or Pre-eclampsia
● Large for gestational age (LGA) babies (also called “macrosomia” or “fat baby")
● delivery complications (shoulder dystocia, birth injuries)
● Needing a C-section
● Stillbirth at term
● Preterm birth
● Newborn complications such as hypoglycemia (low blood sugar), hyperbilirubinemia
● (jaundice), hypocalcemia (low blood calcium), and respiratory distress syndrome
● (breathing problems), some requiring admission to the newborn intensive care unit
● Increases risk that your child will be obese and/or develop diabetes later in life
● Increases your risk for GDM in future pregnancies; for developing diabetes later in life;
● for heart disease; for high blood pressure
How do I know if l have Gestational Diabetes?
Your midwife will recommend testing at around 26 to 28-weeks gestation (and also early testing [14- to 16-weeks’] if you have risk factors). The standard testing method is a two-step process (a Screening test followed by a diagnostic test if necessary):
Step 1: The 50-gram glucose challenge screen. There are no special preparations for this test. In this test, you drink a sugary drink. One hour later, your blood is drawn to measure the glucose level. If your blood glucose is below 140 mg/dl, you have screened NEGATIVE for GDM and no further testing is needed. According to the most recent research, this test will correctly identify about 76 out of 100 women who have gestational diabetes (the other 24 women out of 100 who screen negative do not go on to Step 2 but may actually have gestational diabetes). If your blood glucose is 140 mg/dl or higher, you go on to step 2.
Step 2: The 100-gram glucose tolerance test. For three days before the test, you will be asked to eat an extra carbohydrate serving daily. Prior to the test, you will need to fast (nothing to eat or drink except for sips of water) for 12 hours. When you arrive for testing, a baseline fasting blood glucose sample will be taken. You will then be asked to drink a sugary drink. Blood samples will be taken every hour for the next 3 hours. If two or more of the four blood samples taken are abnormal, you will be diagnosed as having Gestational Diabetes.
What are the benefits of testing?
The main benefit of testing is knowing whether your blood sugar level is normal or not. Knowing this information helps you to make decisions about what to do to have a healthy pregnancy and to protect yourself and your baby from the risks listed above. Also, since having gestational diabetes increases your risk for diabetes and other complications later in life, knowing this will encourage you to monitor your ongoing health.
What are the risks of testing?
● No serious or permanent risks have been identified. The potential adverse effects are:
● Nausea (about 30%)
● Dizziness (11%)
● Headache (9%)
● Chemicals in the glucola drink
● Discomfort from having your blood drawn
● inconvenience of time constraints, especially with the 3-hour test
● The basic unpleasant nature of the test
Are there any alternatives to the two-step testing?
There have been alternative screening tests suggested (candy bar test, jelly bean test, random blood glucose screening, hemoglobin A1C test, fasting blood sugar test, ultrasound).
While there have been studies on these methods, the studies have been small, not duplicated, and the authors of the studies conclude that there is not enough evidence to recommend their method. While these studies show promise, they are not routinely recommended until more research is completed. Because of this, your midwife does not recommend any of these methods.
Acceptable alternatives to the two-step testing include:
1. Skip Step 1 (the screening test) and go directly to the diagnostic test. The “Gold Standard” for the diagnosis of diabetes is either the 75-gram test (2-hour glucose tolerance test) or the 100-gram test (3-hour glucose tolerance test).
2. Monitor your blood sugar several times a day for a minimum of 3 days. Use a blood glucose monitor and test strips to check and record your blood sugar 4 times a day (fasting, and 2-hours after breakfast, lunch, and dinner) for 3 days. Using this method, the goal for fasting blood sugar should be 95 mg/dl or lower, and the 1-hour after meals goal should be 140 mg/dl or lower. Continue to eat your normal foods and write out what you eat on the same log as your blood sugar levels.
3. Decline testing for gestational diabetes
What happens if I am diagnosed with Gestational Diabetes?
If you are diagnosed with Gestational Diabetes, you will be instructed in nutrition changes, exercise, and in monitoring your blood sugar at home several times a day. We will consult with our backup physician as we proceed with your care, depending on the severity of the GDM your care may be partially transferred to our backup physician and you will continue care with All About Babies under “Collaborative Care”. If diet and exercise do not control your blood sugar, you may need medication. If you need medication to control your blood sugar, your care will be completely transferred to our backup physician and you will no longer be eligible for an out of hospital birth at our facility. However, All About Babies will still offer to provide minimal supplemental care, under the discretion of the backup physician, and a midwife will attend your birth in the hospital. Each client’s continued plan of care will be individually discussed between our backup physician and the midwives; you will most likely continue care with All About Babes under “Collaborative Care” but you may no longer be eligible for midwifery care or birth at our Birth Center. Since GDM is associated with increased complications later in life, you should have the glucose tolerance test repeated at 6 to 12 weeks after your baby is born, and then every 1 to 3 years after that.