GESTATIONAL DIABETES is defined as any degree of glucose intolerance with onset or first recognition during pregnancy.1 Approximately 7% of all pregnancies are complicated by gestational diabetes; nearly 200,000 women in the United States are affected each year.2
For most women, the diabetes resolves after giving birth, but having gestational diabetes places the mother and her child at a lifelong risk of developing diabetes (mostly type 2).3 Approximately 60% of obese and 30% of lean women with a history of gestational diabetes are at risk, so take proactive steps promptly.4
This article tells you how a woman is diagnosed, how to help her manage her condition, and what to teach her. Let's start by looking at how gestational diabetes develops.
Hormones to blame
During pregnancy, levels of estrogen, progesterone, and human placental lactogen become elevated. These hormones of pregnancy antagonize the function of insulin, leading to insulin resistance and decreased cellular glucose uptake.
As the placenta grows, more hormones are produced, leading to rising glucose levels and even greater insulin resistance. Normally the pancreas can make additional insulin to overcome such resistance, but when it can't, gestational diabetes results. For most women, after giving birth, the diabetes goes away because the placenta, the major source of insulin resistance, is gone.
Who's at risk?
Women considered at very high risk for developing gestational diabetes should be screened as soon as pregnancy is confirmed.2 Criteria for very high risk include:
- severe obesity
- strong family history of type 2 diabetes
- prior history of gestational diabetes or delivery of large-for-gestational-age infant
- presence of glycosuria
- diagnosis of polycystic ovary syndrome.2
After risk assessment, the healthcare provider may order one- or two-step diagnostic screening. (See One or two steps to testing.) He or she will also refer your patient to a diabetes care expert and advise her to attend diabetes education classes.
Care for the developing baby
Carefully managing the mother's health is the key to having a healthy baby. A woman whose blood glucose levels are much higher than normal is more likely to deliver a large-for-gestational-age infant.
Maternal hyperglycemia leads to fetal hyperglycemia, which then stimulates the fetal pancreas to produce excess insulin. Because insulin is a growth factor for fetal tissue, this excess insulin enlarges the infant's abdominal and chest circumferences. Traumatic delivery of a larger infant causes most of the associated perinatal morbidity.
When maternal blood glucose levels are elevated during pregnancy, the fetus also receives more glucose than required, which stimulates maturation of fetal pancreatic beta cells. At delivery, when the maternal blood supply is eliminated, the infant continues to produce excess insulin that may result in neonatal hypoglycemia. If severe, it can persist and prolong hospital length of stay. Other infant complications, such as respiratory distress syndrome, are less common today due to improved glycemic control and improved monitoring.5
Monitoring the fetus
To head off potential problems, the patient's healthcare provider will closely monitor the fetus throughout the pregnancy with nonstress tests. In addition, ultrasonography helps the healthcare provider assess fetal growth, measure the amount of amniotic fluid, and evaluate the placenta. Amniocentesis can help determine fetal lung maturity.
Risks remain after birth
A woman with gestational diabetes faces a high risk for complications, particularly if she converts to type 2 diabetes after the birth of her baby. Common complications associated with type 2 diabetes can damage her health in the following ways:
- Vision. Elevated placental hormones can cause vascular changes in the eyes. Advise the patient to consult an ophthalmologist.
- Dentition. She's at greater risk for gum disease and tooth loss. Advise her to get regular dental care.
- Cardiovascular. Transient hypertension may predict hypertension later on. Monitor BP regularly and encourage healthy lifestyle changes as directed by her healthcare provider. Screen women with chronic hypertension before pregnancy or at the first prenatal visit.
- Renal function. Gestational diabetes and uncontrolled hypertension can impair renal function. Monitor for proteinuria and elevated serum creatinine levels.
- Neuropathy. Autonomic neuropathy might lead to nausea and vomiting, affecting fetal nutrition.
Individually tailored blood glucose monitoring throughout the day can help your patient control her glucose levels. Testing is generally quick and easy. Glucose levels need to be tracked to evaluate the patient's response to the protocol she's following. (See Suggested target glucose values for gestational diabetes.)
Educating the mother
Learning to deal with pregnancy complicated by diabetes can be difficult and stressful. Your patient needs help from a healthcare professional who's an expert in diabetes care. Diabetes education classes also provide information and emotional support. Using these resources, she'll learn to manage her condition and her medications to keep herself and her baby healthy before and after childbirth. First, let's consider her diet.
Planning a healthy diet
Because nutritional needs change during pregnancy, meal planning and good nutritional habits are vital. Your patient's goal will be to consume enough calories and nutrients for pregnancy without episodes of hypoglycemia or hyperglycemia. She should try for three meals and two to four small snacks per day, taking her food preferences into account.
Give your patient these tips:
- Eat a well-balanced diet, including carbohydrates, protein, iron, calcium, vitamins, and sodium. Consult with a dietitian and certified diabetes educator for an individualized diet plan.
- Eat foods high in fiber.
- Avoid foods high in refined sugar and fat.
- Maintain a healthy fluid intake, approximately eight 8-ounce (235-mL) glasses of water per day.
- Make weight control the focus of serving sizes, label reading, eating out, and cooking at home. You'll determine your weight goal with your healthcare provider.
Regular exercise helps not only to control glucose levels but also to manage weight while reducing insulin resistance. Encourage the patient to choose an activity she enjoys, keeping in mind that pregnancy isn't the best time for a previously sedentary woman to initiate strenuous exercise. Walking helps to ease postmeal increases in blood sugar and to keep insulin needs in check.
Teach your patient the signs and symptoms of hypoglycemia and hyperglycemia, as well as appropriate interventions.
Discourage alcohol use and smoking during pregnancy to lessen the risk of central nervous system abnormalities and low birth weight. Alcohol and smoking can lower glucose levels and suppress appetite.
Managing with medications
The goal of drug therapy is to prevent fetal hyperinsulinemia without endangering the development of the fetus. When the mother's glucose level is normalized, the fetus doesn't respond to the mother's elevated glucose level with fetal hyperinsulinemia.
An oral agent shouldn't cross the placental barrier or be found in cord blood. Glyburide (DiaBeta), a second-generation sulfonylurea, is believed to be safe in pregnancy, but thiazolidinediones are believed to freely cross the placenta.6
Approximately 20% to 50% of women with gestational diabetes need insulin therapy to achieve euglycemia. Balancing food with insulin is key to keeping glucose within normal ranges. Lispro (Humalog) and aspart (NovoLog), both rapid-acting insulin analogues, are currently available. Both have a more rapid onset of action and are good for avoiding postmeal hyperglycemia as well as late hypoglycemic events.6
Initiation of insulin treatment as needed based on glucose readings and A1C to maintain levels at or below 90 mg/dL before meals and at or below 120 mg/dL 2 hours after meals has been shown to reduce the risk of fetal and maternal complications.2 No matter which insulin is selected, the patient will need intensive instruction from a diabetes educator.
Inform your patient about the benefits of breastfeeding, which provides proper nutrients and maternal antibodies. Breastfeeding may also lower the risk that the infant will become obese or hypertensive or develop type 2 diabetes.2
Tell your patient that breastfeeding has health benefits for her as well. Besides speeding weight loss, it imparts long-term health benefits, including decreased risk of ovarian and premenopausal breast cancer and improved bone mineralization.7 Answer questions about breastfeeding early on and have lactation support available.
Ongoing diabetes risk
Although insulin needs decrease significantly after birth, blood glucose levels may need to be monitored during this period. Women with a history of gestational diabetes should be screened for diabetes 6 to 12 weeks postpartum.2
Screening at least every 1 to 2 years is suggested for a woman who's had gestational diabetes, but annual testing is strongly recommended for any women who have signs and symptoms in the postpartum period.3 Preconception care for women with a history of gestational diabetes ideally should begin 3 to 6 months before conception to allow sufficient time to stabilize the mother's health and optimize glycemic control.
Encourage your patient to adhere to a healthy diet, maintain a healthy body weight, exercise each day, and keep her follow-up appointments. She may benefit from joining a support group, consulting a dietitian, and keeping a food intake diary. In addition, advise her to:
- try to reach prepregnancy weight 6 to 12 months after the baby is born. Then, if she's still overweight, she should attempt to lose at least 5% to 7% of her body weight slowly over time.3
- inform her baby's pediatrician that she's had gestational diabetes.
- make healthy food choices: fruits and vegetables, fish, lean meats, dry beans and peas, whole grains, and low fat or skim milk and cheese. She should drink plenty of water.
- take any medications exactly as prescribed, and perform glucose self-monitoring as directed by her healthcare provider.
- have annual blood glucose testing and contact her healthcare provider if she develops signs and symptoms of hyperglycemia, such as blurred vision.
- talk to her healthcare provider if she plans to become pregnant again so her condition can be monitored closely.
Encourage the new mother to take care of herself. Remind her that she's worked hard to deliver a healthy baby, and careful diabetes management will help ensure successful future pregnancies and decrease her risk of long-term diabetes complications.