Glucose Test During Pregnancy for Gestational Diabetes

Congratulations! A baby is on the way. Your nine months will be filled with preparations, from decorating the nursery to stocking up on bibs and booties to going for regular checkups to ensure that you and your baby are as healthy as possible. One of the tests that you’ll have during this time is to check for gestational diabetes.

A few weeks ago, we looked at Type 1 and Type 2 diabetes. Gestational diabetes, which is growing more common among pregnant women, will be our focus this week.

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What is gestational diabetes?
Gestational diabetes, or GDM for short, is diabetes that occurs during pregnancy. In fact, it only occurs during pregnancy. (Gestational diabetes is not the same as diabetes in women who have existing diabetes and become pregnant). Diabetes, as most of you know, is a condition in which blood glucose levels go too high. High blood glucose levels can be harmful to you and, in the case of pregnancy, to your unborn child. Fortunately, blood glucose, or sugar, levels can be controlled during pregnancy, and in most instances, high blood sugar levels return to normal after the baby is delivered. According to the National Institutes of Health, up to 10% of pregnant women in the United States have gestational diabetes.

What causes gestational diabetes?
A lot of changes occur in the body during pregnancy, many of them occurring due to widely fluctuating hormone levels. The placenta, which is what connects the baby to the mother’s uterine lining, makes various hormones, and while this is a good thing, these hormones can sometimes make it hard for the body’s insulin to work properly (a condition called insulin resistance). As a result, blood sugar levels can start to climb in women who cannot produce enough insulin to deal with the insulin resistance.

How do you know if you have gestational diabetes?
Because gestational diabetes may not cause any symptoms, the American Diabetes Association recommends that all pregnant women get checked for it between weeks 24 and 28 of pregnancy. If you are at high risk for gestational diabetes (for example, you have a family history of diabetes or are overweight), you may be checked sooner. Your doctor (likely an obstetrician) should be discussing your prenatal care with you, and that discussion should include mention of gestational diabetes, including getting tested.

Do some women have a higher risk of getting gestational diabetes than others?
The answer is “yes.” Just as there are risk factors for Type 2 diabetes, there are risk factors for gestational diabetes. In fact, the risk factors are surprisingly similar.

• Being overweight or obese
• Being over the age of 25
• Having had gestational diabetes before
• Having had a baby weighing 9 pounds or more at birth
• Having parent or sibling with Type 2 diabetes
• Being of African, Asian, Hispanic, Pacific Islander, or Native American descent

However, any pregnant woman can get gestational diabetes, even if she doesn’t have the above risk factors, so getting tested for this is very important.

What is the test for gestational diabetes?
Blood tests done at the lab are used to diagnose gestational (a blood glucose meter can’t be used to diagnose this condition). There are a couple of different ways to check for gestational diabetes. The first test requires you to simply show up at the doctor’s office. After having your fasting glucose level checked, you’ll drink a sugary drink containing 50 grams of glucose; your blood sugar will be checked one hour later.

If the results from this test are too high, you’ll likely have an oral glucose tolerance test. With this test, you’ll need to fast 8 to 12 hours beforehand (usually overnight). When you show up at the lab or doctor’s office, you’ll have your blood sugar checked. Then, you’ll drink a sugary drink containing 100 grams of glucose. Your blood sugar will be checked again three more times every 60 minutes. The entire test takes about three hours.

Your doctor will determine which test is best for you to have initially, too. The test is pretty straightforward, but keep in mind that the drink is very sweet (like a soda), and it can make some women feel nauseated or lightheaded.

What do the results mean?
A normal glucose tolerance test result is less than 140 mg/dl one hour after drinking the sugar drink. This result means that you don’t have gestational diabetes. If your result is above 140 mg/dl, you’d go on to have the oral glucose tolerance test. With the three-hour test, blood glucose results that indicate gestational diabetes are:

Fasting: greater than 95 mg/dl
1 hour: greater than 180 mg/dl
2 hour: greater than 155 mg/dl
3 hour: greater than 140 mg/dl

If only one of the test results is higher than normal, you’ll likely be rechecked again in four weeks. But if two or more tests are higher than normal, you’ll be diagnosed with gestational diabetes.

Can you lower your risk for developing gestational diabetes?
There are steps that you can take to lower your risk for this condition. Prevention starts long before you become pregnant, and involves lifestyle changes. If you are overweight, work on losing weight. This means following a healthy eating plan. A healthy eating plan limits sweets and sugary beverages, and includes fiber from fruits, vegetables, legumes, and whole grains. One study showed that increasing fiber by 10 grams per day lowered the risk of getting gestational diabetes by 26%. The other key factor is to become (and stay) physically active. Physical activity helps to lower insulin resistance. If you need help getting started with an eating plan or physical activity (or both), ask your doctor for a referral to a dietitian or a diabetes educator.

Life with diabetes sometimes feels like I she’s at war with her body, says Amy Mercer. Bookmark DiabetesSelfManagement.com and tune in tomorrow to read more.