Gestational Diabetes

Definition

Gestational diabetes develops during pregnancy (gestation). Like other types of diabetes, gestational diabetes affects how your cells use sugar (glucose). Gestational diabetes causes high blood sugar that can affect your pregnancy and your baby's health.
Any pregnancy complication is concerning, but there's good news. Expectant moms can help control gestational diabetes by eating healthy foods, exercising and, if necessary, taking medication. Controlling blood sugar can prevent a difficult birth and keep you and your baby healthy.
In gestational diabetes, blood sugar usually returns to normal soon after delivery. But if you've had gestational diabetes, you're at risk for type 2 diabetes. You'll continue working with your health care team to monitor and manage your blood sugar.

Symptoms

For most women, gestational diabetes doesn't cause noticeable signs or symptoms.

Causes

Researchers don't know why some women develop gestational diabetes. To understand how gestational diabetes occurs, it can help to understand how pregnancy affects your body's glucose processing.
Your body digests the food you eat to produce sugar (glucose) that enters your bloodstream. In response, your pancreas — a large gland behind your stomach — produces insulin. Insulin is a hormone that helps glucose move from your bloodstream into your body's cells, where it's used as energy.
During pregnancy, the placenta, which connects your baby to your blood supply, produces high levels of various other hormones. Almost all of them impair the action of insulin in your cells, raising your blood sugar. Modest elevation of blood sugar after meals is normal during pregnancy.
As your baby grows, the placenta produces more and more insulin-blocking hormones. In gestational diabetes, the placental hormones provoke a rise in blood sugar to a level that can affect the growth and welfare of your baby. Gestational diabetes usually develops during the last half of pregnancy — sometimes as early as the 20th week, but generally not until later.\

Risk factors

Any woman can develop gestational diabetes, but some women are at greater risk. Risk factors for gestational diabetes include:

• Age greater than 25. Women older than age 25 are more likely to develop gestational diabetes.
• Family or personal health history. Your risk of developing gestational diabetes increases if you have prediabetes — slightly elevated blood sugar that may be a precursor to type 2 diabetes — or if a close family member, such as a parent or sibling, has type 2 diabetes. You're also more likely to develop gestational diabetes if you had it during a previous pregnancy, if you delivered a baby who weighed more than 9 pounds (4.1 kilograms), or if you had an unexplained stillbirth.
• Excess weight. You're more likely to develop gestational diabetes if you're significantly overweight with a body mass index (BMI) of 30 or higher.
• Nonwhite race. For reasons that aren't clear, women who are black, Hispanic, American Indian or Asian are more likely to develop gestational diabetes.

Complications

Most women who have gestational diabetes deliver healthy babies. However, gestational diabetes that's not carefully managed can lead to uncontrolled blood sugar levels and cause problems for you and your baby, including an increased likelihood of needing a C-section to deliver.
Complications that may affect your baby
If you have gestational diabetes, your baby may be at increased risk of:

• Excessive birth weight. Extra glucose in your bloodstream crosses the placenta, which triggers your baby's pancreas to make extra insulin. This can cause your baby to grow too large (macrosomia). Very large babies — those that weigh 9 pounds or more — are more likely to become wedged in the birth canal, sustain birth injuries or require a C-section birth.
• Early (preterm) birth and respiratory distress syndrome. A mother's high blood sugar may increase her risk of early labor and delivering her baby before its due date. Or her doctor may recommend early delivery because the baby is large.
  Babies born early may experience respiratory distress syndrome — a condition that makes breathing difficult. Babies with this syndrome may need help breathing until their lungs mature and become stronger. Babies of mothers with gestational diabetes may experience respiratory distress syndrome even if they're not born early.
  
• Low blood sugar (hypoglycemia). Sometimes babies of mothers with gestational diabetes develop low blood sugar (hypoglycemia) shortly after birth because their own insulin production is high. Severe episodes of hypoglycemia may provoke seizures in the baby. Prompt feedings and sometimes an intravenous glucose solution can return the baby's blood sugar level to normal.
• Type 2 diabetes later in life. Babies of mothers who have gestational diabetes have a higher risk of developing obesity and type 2 diabetes later in life.

Untreated gestational diabetes can result in a baby's death either before or shortly after birth.

Complications that may affect you

Gestational diabetes may also increase the mother's risk of:

• High blood pressure and preeclampsia. Gestational diabetes raises your risk of high blood pressure, as well as, preeclampsia — a serious complication of pregnancy that causes high blood pressure and other symptoms that can threaten the lives of both mother and baby.
• Future diabetes. If you have gestational diabetes, you're more likely to get it again during a future pregnancy. You're also more likely to develop type 2 diabetes as you get older. However, making healthy lifestyle choices such as eating healthy foods and exercising can help reduce the risk of future type 2 diabetes.
  Of those women with a history of gestational diabetes who reach their ideal body weight after delivery, fewer than 1 in 4 eventually develops type 2 diabetes.
  
  
  

  Tests and diagnosis

  Medical experts haven't agreed on a single set of screening guidelines for gestational diabetes. Some question whether gestational diabetes screening is needed if you're younger than 25 and have no risk factors. Others say that screening all pregnant women is the best way to identify all cases of gestational diabetes.
  

  When to screen

  Your doctor will likely evaluate your risk factors for gestational diabetes early in your pregnancy.
  If you're at high risk of gestational diabetes — for example, your body mass index (BMI) before pregnancy was 30 or higher or you have a mother, father, sibling or child with diabetes — your doctor may test for diabetes at your first prenatal visit.
  If you're at average risk of gestational diabetes, you'll likely have a screening test during your second trimester — between 24 and 28 weeks of pregnancy.
  

  Routine screening for gestational diabetes

Screening for diabetes mellitus during pregnancy

Gestational diabetes
The following 2-step screening system for gestational diabetes is currently recommended in the United States:

• 50-g, 1-hour glucose challenge test (GCT)
• 100-g, 3-hour oral glucose tolerance test (OGTT) - For patients with an abnormal GCT result

Alternatively, for high-risk women or in areas in which the prevalence of insulin resistance is 5% or higher (eg, the southwestern and southeastern United States), a 1-step approach can be used by proceeding directly to the 100-g, 3-hour OGTT.
The US Preventive Services Task Force (USPSTF) recommends screening for gestational diabetes mellitus after 24 weeks of pregnancy. The recommendation applies to asymptomatic women with no previous diagnosis of type 1 or type 2 diabetes mellitus.^{[4, 5]} The recommendation does not specify whether the 1-step or 2-step screening approach would be preferable.
Type 1 diabetes

• The disease is typically diagnosed during an episode of hyperglycemia, ketosis, and dehydration
• It is most commonly diagnosed in childhood or adolescence; the disease is rarely diagnosed during pregnancy
• Patients diagnosed during pregnancy most often present with unexpected coma - Early pregnancy may provoke diet and glycemic control instability in patients with occult diabetes

Type 2 diabetes
According to the American Diabetes Association’s "Standards of Medical Care in Diabetes--2010,"^{[6, 7]} the presence of any one of the following criteria supports the diagnosis of diabetes mellitus:

• Hemoglobin A1C (HbA1C) = 6.5%
• Fasting plasma glucose = >126 mg/dL (7.0 mmol/L)
• A 2-hour plasma glucose level = 200 mg/dL (11.1 mmol/L) during a 75-g OGTT
• A random plasma glucose level = 200 mg/dL (11.1 mmol/l) in a patient with classic symptoms of hyperglycemia or hyperglycemic crisis

In the absence of unequivocal hyperglycemia, a diagnosis based on any of the first 3 criteria should be confirmed by repeat testing on a different day.
Prediabetes
Women with prediabetes identified before pregnancy should be considered at extremely high risk for developing gestational diabetes mellitus during pregnancy. As such, they should receive early (first-trimester) diabetic screening.

Postdiagnostic testing

Once the diagnosis of diabetes is established in a pregnant woman, continued testing for glycemic control and diabetic complications is indicated for the remainder of the pregnancy.
First-trimester laboratory studies

• HbA1C
• Blood urea nitrogen (BUN)
• Serum creatinine
• Thyroid-stimulating hormone
• Free thyroxine levels
• Spot urine protein-to-creatinine ratio
• Capillary blood sugar levels

Second-trimester laboratory studies

• Spot urine protein-to-creatinine study in women with elevated value in first trimester
• Repeat HbA1C
• Capillary blood sugar levels

Ultrasonography

• First trimester - Ultrasonographic assessment for pregnancy dating and viability
• Second trimester - Detailed anatomic ultrasonogram at 18-20 weeks and a fetal echocardiogram if the maternal glycohemoglobin value was elevated in the first trimester
• Third trimester - Growth ultrasonogram to assess fetal size every 4-6 weeks from 26-36 weeks in women with overt preexisting diabetes; perform a growth ultrasonogram for fetal size at least once at 36-37 weeks for women with gestational diabetes mellitus

Electrocardiography
If maternal diabetes is longstanding or associated with known microvascular disease, obtain a baseline maternal electrocardiogram (ECG) and echocardiogram.

Blood sugar testing after you give birth

Your doctor will check your blood sugar after delivery and again in six to 12 weeks to make sure that your level has returned to normal. If your tests are normal — and most are — you'll need to have your diabetes risk assessed at least every three years.
If future tests indicate diabetes or prediabetes — a condition in which your blood sugar is higher than normal, but not high enough to be considered diabetes — talk with your doctor about increasing your prevention efforts or starting a diabetes management plan.

Treatments and drugs

It's essential to monitor and control your blood sugar to keep your baby healthy and avoid complications during pregnancy and delivery. You'll also want to keep a close eye on your future blood sugar levels. Your treatment strategies may include:

• Monitoring your blood sugar. While you're pregnant, your health care team may ask you to check your blood sugar four to five times a day — first thing in the morning and after meals — to make sure your level stays within a healthy range. This may sound inconvenient and difficult, but it'll get easier with practice.
  To test your blood sugar, you draw a drop of blood from your finger using a small needle (lancet), then place the blood on a test strip inserted into a blood glucose meter — a device that measures and displays your blood sugar level.
  Your health care team will monitor and manage your blood sugar during labor and delivery. If your blood sugar rises, your baby's pancreas may release high levels of insulin — which can cause low blood sugar in your baby right after birth.
  Follow-up blood sugar checks are also important. Having gestational diabetes increases your risk of developing type 2 diabetes later in life. Work with your health care team to keep an eye on your levels. Maintaining health-promoting lifestyle habits, such as a healthy diet and regular exercise, can help reduce your risk.
  
• Healthy diet. Eating the right kinds of food in healthy portions is one of the best ways to control your blood sugar and prevent too much weight gain, which can put you at higher risk of complications. Doctors don't advise losing weight during pregnancy — your body is working hard to support your growing baby. But your doctor can help you set weight gain goals based on your weight before pregnancy.
  A healthy diet focuses on fruits, vegetables and whole grains — foods that are high in nutrition and fiber and low in fat and calories — and limits highly refined carbohydrates, including sweets. No single diet is right for every woman. You may want to consult a registered dietitian or a diabetes educator to create a meal plan based on your current weight, pregnancy weight gain goals, blood sugar level, exercise habits, food preferences and budget.
  
• Exercise. Regular physical activity plays a key role in every woman's wellness plan before, during and after pregnancy. Exercise lowers your blood sugar by stimulating your body to move glucose into your cells, where it's used for energy. Exercise also increases your cells' sensitivity to insulin, which means your body will need to produce less insulin to transport sugar.
  As an added bonus, regular exercise can help relieve some common discomforts of pregnancy, including back pain, muscle cramps, swelling, constipation and trouble sleeping. Exercise can also help get you in shape for the hard work of labor and delivery.
  With your doctor's OK, aim for moderately vigorous exercise on most days of the week. If you haven't been active for a while, start slowly and build up gradually. Walking, cycling and swimming are good choices during pregnancy. Everyday activities such as housework and gardening also count.
  
• Medication.  Insulin
  The goal of insulin therapy during pregnancy is to achieve glucose profiles similar to those of nondiabetic pregnant women. In gestational diabetes, early intervention with insulin or an oral agent is key to achieving a good outcome when diet therapy fails to provide adequate glycemic control.
  Glyburide and metformin
  The efficacy and safety of insulin have made it the standard for treatment of diabetes during pregnancy. Diabetic therapy with the oral agents glyburide and metformin, however, has been gaining in popularity. Trials have shown these 2 drugs to be effective, and no evidence of harm to the fetus has been found, although the potential for long-term adverse effects remains a concern.
  
• Close monitoring of your baby. An important part of your treatment plan is close observation of your baby. Your doctor may monitor your baby's growth and development with repeated ultrasounds or other tests. If you don't go into labor by your due date — or sometimes earlier — your doctor may induce labor. Delivering after your due date may increase the risk of complications for you and your baby.

Prevention

There are no guarantees when it comes to preventing gestational diabetes — but the more healthy habits you can adopt before pregnancy, the better. If you've had gestational diabetes, these healthy choices may also reduce your risk of having it in future pregnancies or developing type 2 diabetes down the road.

• Eat healthy foods. Choose foods high in fiber and low in fat and calories. Focus on fruits, vegetables and whole grains. Strive for variety to help you achieve your goals without compromising taste or nutrition. Watch portion sizes.
• Keep active. Exercising before and during pregnancy can help protect you from developing gestational diabetes. Aim for 30 minutes of moderate activity on most days of the week. Take a brisk daily walk. Ride your bike. Swim laps.
  If you can't fit a single 30-minute workout into your day, several shorter sessions can do just as mu