Gestational diabetes: an introduction
Gestational diabetes affects approximately 2% to 10% of US women during pregnancy. However, since the way we think about and diagnose gestational diabetes has recently changed, we expect these rates to increase (potentially up to 20%). In fact, with more women becoming pregnant at an older age and with increasing numbers of women being overweight or obese, it is often the case that type 2 diabetes is first diagnosed at pregnancy. For this reason, the American Diabetes Association now recommends that all pregnant women be screened for type 2 diabetes very early in pregnancy and, if diabetes is present, that it be considered undiagnosed type 2 diabetes.1.2
For many women, gestational diabetes will disappear following birth. However, this is not always the case. Right after giving birth, about 5% to 10% of women with gestational diabetes are diagnosed with diabetes, usually type 2 diabetes. Research has shown that women who do develop gestational diabetes have an increased risk (35% to 60%) of developing type 2 diabetes within the 10 to 20 years following the pregnancy. Gestational diabetes is also associated with increased health problems for children. Children of mothers who had gestational diabetes have an increased risk for becoming obese and for eventually developing type 2 diabetes.2
What causes gestational diabetes?
Gestational diabetes can be caused by the hormones that are released by the body during pregnancy that reduce insulin production. Like type 2 diabetes, being overweight or obese, having a family history of type 2 diabetes, fat distribution in the waist-to-hip area, a sedentary lifestyle, and smoking can all increase risk for gestational diabetes. In addition to these, having a previous large baby (>9 lbs) also increases the risk for gestational diabetes.3
Who should be screened for gestational diabetes and when should screening occur?
Screening for gestational diabetes is recommended at the first prenatal visit for women who are at high risk for type 2 diabetes. This refers to women who are overweight (BMI ≥25 kg/m2) and have additional risk factors, including1:
- Physical inactivity
- Family history of type 2 diabetes (a first-degree relative with diabetes)
- Member of a high-risk ethnic/racial group (African American, Latino, Native American, Asian American, Pacific Islander)
- Women who previously delivered a baby with high birth weight (>9 lbs) or who was previously diagnosed with gestational diabetes
- High blood pressure (≥140/90 mmHg) or being treated for high blood pressure
- HDL cholesterol level 250 mg/dL
- Woman with polycystic ovarian syndrome
- A1C ≥5.7%, impaired glucose tolerance, or impaired fasting glucose on a previous test
- Other clinical conditions associated with insulin resistance (eg, severe obesity)
- A history of cardiovascular disease
Women who have not previously been diagnosed with diabetes should be screened between 24 and 28 weeks of pregnancy. Additionally, women who have been diagnosed with gestational diabetes should be screened for persistent diabetes at 6 to 12 weeks after delivery and those with a history of gestational diabetes should be screened for diabetes and prediabetes regularly every 3 years.1
What kind of test is used to determine gestational diabetes?
Gestational diabetes is screened for using an oral glucose tolerance test,a blood test taken after drinking a special concentrated glucose drink. This test can be done using a one- or two-step approach. In the one-step approach, screening is done 2 hours after taking a 75-gram glucose drink. In the two-step approach, screening is done 1 hour after taking a 50-gram glucose drink, followed by a second screening done 3 hours after taking a 100-gram glucose drink.1
Can gestational diabetes result in complications with my pregnancy?
Gestational diabetes can result in serious complications that may affect both mother and baby. These include4:
- High birth weight. Increased birth weight (greater than 9 lbs), which poses increased risk of injury to the mother and baby during birth and increases the likelihood of cesarean section.
- Preeclampsia. Increased risk of preeclampsia, a condition characterized by elevated blood pressure, with increased protein in the urine, which may lead to eclampsia, a condition involving life-threatening seizure.
- Increased risk in child for obesity later in life. Children of mothers who had gestational diabetes have an increased risk for becoming obese and for eventually developing type 2 diabetes.
How is gestational diabetes treated?
The most significant complication of gestational diabetes is having a large baby (>9 lbs), which increases the risk for injury to mother and child during delivery. Elevated blood sugar can increase the weight of a developing fetus. Therefore, the goal of treatment in gestational diabetes is to control blood sugar.1
The goals for blood glucose control for a woman with gestational diabetes include keeping before-meal blood glucose levels ≤95 mg/dL, and either post-meal blood glucose at:
- ≤140 mg/dL at 1 hour after eating, or
- ≤120 mg/dL at 2 hours after eating
Therefore, regular blood glucose monitoring should be part of the care plan for a woman with gestational diabetes. Blood sugar monitoring will give you the information you need to tell if your blood sugar is under control. If you cannot achieve blood sugar control using a healthy, calorie appropriate eating plan, you may need to take insulin injections.1
Women with pre-existing type 2 diabetes who become pregnant should aim for the following blood glucose goals, if they can be achieved without hypoglycemia:
- Before meals, at bedtime, and overnight: 60-99 mg/dL
- After meals (peak blood glucose): 100-129 mg/dL
Additionally, preconception care for planned pregnancies is important because uncontrolled blood glucose can results in deformities in the developing fetus. The goal of preconception care should be maintaining normal blood sugar through diet, insulin therapy, and blood glucose monitoring. Studies have shown that blood glucose control during preconception can lower the risk for fetal malformation.1
Treatment for gestational diabetes typically requires making changes in diet to lower blood sugar and may require taking insulin injections. Most noninsulin diabetes treatments, including oral diabetes medications, are not recommended for use in pregnant women. Additionally, other classes of drugs frequently used to treatment complications of diabetes, including angiotensin-converting-enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) used to treat high blood pressure and statins, used to treat lipid abnormalities, are not safe to use during pregnancy. In addition to healthy eating, physical activity may help you control your blood sugar. However, it is not a necessary part of treatment.1
A healthy, calorie-appropriate eating plan to help control blood sugar . Getting the right amount of calories and eating a healthy diet is an essential part of the treatment plan for a women with gestational diabetes. You should work with your diabetes care team, including your doctor and a registered dietitian to make sure that your food plan gives you the right amount of nutrients to support your pregnancy and to achieve your blood glucose targets, without causing weight loss or excessive weight gain. Work with your care team to ensure that you take in the right amount of calories to support your energy needs, with appropriate weight gain during pregnancy. Determining specific calorie goals for your healthy eating plan will depend on several individual factors, including whether you are overweight or obese and how active you are. For women who are overweight or obese, some calorie and carbohydrate restriction during pregnancy may be appropriate. In general, if you are obese a small weight gain of 15 lbs may be appropriate during pregnancy, while greater weight gain of up to 40 lbs may be appropriate for women who are underweight.5
Whatever food plan you and your dietitian determine should be appropriate to your culture and the foods that you are accustomed to eating. It should also be individualized according to your size, weight gain, and activity level, and should be adjusted as needed throughout your pregnancy.
Your dietitian will work with you during your pregnancy to help you learn about and adopt:
- Healthy food choices
- Portion control
- Cooking and food preparation practices
All of these healthy eating practices can be continued later after pregnancy to help you prevent development of type 2 diabetes, achieve and maintain a healthy body weight, and reduce your risk for cardiovascular disease and cancer and other health conditions commonly associated with type 2 diabetes.
In addition to a healthy, calorie-appropriate eating plan, regular physical activity should also be a part of your treatment plan for gestational diabetes. You should aim to get at least 30 minutes of physical activity every day. You can accomplish this by taking a brisk walk every day or by doing less strenuous seated exercises. Talk to your diabetes care team members about what types of physical activity are appropriate for you during your pregnancy.5
Can gestational diabetes be prevented?
As with type 2 diabetes, gestational diabetes can be prevented by maintaining a healthy body weight. In addition, getting regular physical activity may help prevent development of the disorder.3