Diabetes During Pregnancy

• Diabetes during pregnancy


  Encompasses a range of disease entities that includes gestational diabetes and overt diabetes mellitus
• Types of diabetes during pregnancy

  • Pregestational diabetes
  • Gestational diabetes
• Pregestational diabetes


  Patients diagnosed with type 1 and type 2 diabetes mellitus prior to pregnancy
• Gestational diabetes


  Patients diagnosed with carbohydrate intolerance during pregnancy
• Gestational diabetes mellitus (GDM) is an impairment in carbohydrate metabolism that first manifests during pregnancy</b>
• GDM


  • Patients may have borderline carbohydrate metabolism impairment at baseline or be entirely normal in the nonpregnant state
  • During pregnancy, human chorionic somatomammotropin (a.k.a. human placental lactogen) and other hormones produced by the placenta act as anti-insulin agents leading to increased insulin resistance and generalized carbohydrate intolerance
  • This increased insulin resistance occurs in all pregnant women, but those in whom the balance between insulin function and resistance is tipped beyond a usual carbohydrate metabolism state will have elevated postprandial and occasionally fasting glucose
  • Beta cell function in the pancreas may also play a part, with beta cell hypertrophy occurring in the first half of pregnancy that enables enough insulin production to overcome the increased insulin resistance produced by the placental hormones
• Because these placental hormones increase in volume with the size and function of the placenta, the carbohydrate metabolism abnormalities usually are not apparent until the late second trimester or early third trimester
• Women with GDM generally are not at increased risk for congenital anomalies like women with pregestational diabetes
• Risks for women with GDM


  • Increased risk of fetal macrosomia and birth injuries
  • Increased risk of neonatal hypoglycemia, hypocalcemia, hyperbilirubinemia, and polycythemia
  • to 10-fold increased risk of developing type 2 diabetes mellitus (T2DM) during their lifetime
• Epidemiology of GDM


  Incidence ranges from 1% to 12% of pregnant women depending on the population, often reported to range between 5% and 8% in the United States
• Groups with higher rates of GDM

  • Hispanic/Latina
  • Asian/Pacific Islander
  • Native American
• Paternal race/ethnicity in these three groups is associated with GDM
• Initial studies found higher rates of GDM among African American women, but subsequent studies controlling for maternal BMI have found little difference in incidence between African Americans and Caucasians
• Other risk factors for GDM

  • Increasing maternal age
  • Obesity
  • Family history of diabetes
  • History of a previous infant weighing more than 4,000 g
  • Previous stillborn infant
• Diagnostic evaluation for GDM

  • Best time to screen is at the end of the second trimester between 24 and 28 weeks' gestation in women with low risk
  • Patients with one or more risk factors should be screened at their first prenatal visit as part of initial prenatal laboratory tests
• Screening methods for GDM

  • 50-g glucose load with 1-hour plasma glucose measurement
  • 100-g, 3-hour oral glucose tolerance test
• Screening threshold for 50-g glucose load

  Greater than 130 or 140 mg/dL is considered positive, with recently proposed thresholds of 130 or 135 mg/dL
• Diagnosis of GDM


  • 100-g, 3-hour oral glucose tolerance test
  • Two or more of the four values (fasting, 1-hour, 2-hour, 3-hour) are elevated
• Recently, the ADA, WHO, and IADPSG have recommended a single test with a 75-g glucose load and 1-hour and 2-hour blood glucose assessments, with one elevated value diagnosing GDM
• Treatment for GDM


  • Recommended diet of 2,200 calories per day with 200-220 g of carbohydrates per day
  • Meal plan based on 30-35 kcal/kg of ideal body weight
  • Blood glucose monitoring 4 times per day (fasting and 3 postprandial)
  • Mild exercise, usually postprandial walking
• Medication for GDM


  • Insulin (short-acting and intermediate-acting) if diet and exercise do not control blood glucose
  • Oral hypoglycemic agents (glyburide, metformin) are considered experimental
• Fetal monitoring is required for A2 GDM patients who are started on medication
• Hypoglycemic agents were not used in pregnancy due to concerns regarding fetal hypoglycemia
• Recent studies indicate that in some patients, adequate blood glucose control can be achieved without particular harm to the fetus
• Oral agents such as glyburide or metformin are now being used by some clinicians due to the ease of patient administration and possibly improved compliance
• There have been only three relatively small randomized prospective trials on glyburide, and these were not adequately powered to examine all important neonatal outcomes, and long-term results are not yet available
• One of the studies did find an improvement in several neonatal outcomes in those treated with insulin as compared to glyburide
• A recent randomized trial comparing metformin and insulin demonstrated no differences in outcomes
• ACOG still considers the use of oral hypoglycemic agents during pregnancy to be experimental
• Fetal monitoring in A2 GDM patients

  1. Nonstress test (NST) or modified biophysical profile (BPP) between 32 and 36 weeks' gestation, continued until delivery on a weekly or biweekly basis

  2. Obstetric ultrasound for estimated fetal weight (EFW) between 34 and 37 weeks
• It is not common to offer fetal monitoring to A1 GDM patients who are well-controlled on diet alone
• The decision to offer A1 GDM patients an ultrasound for EFW varies among practitioners
• The intrapartum management of diet-controlled gestational diabetic patients does not differ from that of nondiabetic women, provided that a random glucose check on admission does not reveal significant hyperglycemia
• It is unclear whether well-controlled gestational diabetic patients have any particular increased risk for peripartum complications other than the theoretical risk of macrosomia
• Scheduled delivery (typically via induction of labor) at 39 weeks of gestation is common in patients on insulin or a hypoglycemic agent (class A2 GDM)
• One concern about allowing their pregnancies to proceed is that there may be an increased risk of hypoglycemia as their placental function decreases toward the end of pregnancy
• Delivery management for patients on insulin or hypoglycemic agent

  1. Brought in to labor and delivery at 39 weeks

  2. Discontinue long-acting hypoglycemic agents

  3. Monitor blood glucose every hour

  4. Use dextrose and insulin drips if necessary to maintain blood glucose within reference limits (<120 mg/dL)
• Patients with poor glycemic control are offered delivery between weeks 37 and 39 after verification of fetal lung maturity
• Patients who have an estimated fetal weight above 4,000 g have increased risks of shoulder dystocia and their labor curves should be followed closely
• Some clinicians offer these patients an elective cesarean birth, but more commonly, elective cesarean delivery is offered to those with an EFW greater than 4,500 g