Review Note

Gestational Diabetes Mellitus (GDM)

• GDM is defined as carbohydrate intolerance that develops or is first recognized during pregnancy.
• It has serious adverse effects for both the mother and the neonate.

• Pregnancy-induced changes in maternal carbohydrate metabolism lead to insulin resistance due to placental hormones.
• The body compensates with increased insulin secretion; however, in cases of inadequate compensation, gestational diabetes develops.

• Routine screening occurs between 24-28 weeks using the glucose challenge test (GCT) or oral glucose tolerance test (OGTT).
• Early screening may be recommended for high-risk women, including those with a history of gestational diabetes, obesity, or a family history of diabetes.

• Macrosomia (large for gestational age) and shoulder dystocia can occur.
• Structural malformations, including CNS, cardiac, skeletal, renal, gastrointestinal, and pulmonary defects.
• Intrauterine fetal death (IUFD) or neonatal death.
• Neonatal respiratory distress syndrome, hypoglycemia, and hyperbilirubinemia.

• Increased risk of gestational hypertension, pre-eclampsia, and polyhydramnios.
• Higher likelihood of instrumental deliveries, episiotomy, and caesarean section (LSCS).
• Increased risk of developing type 2 diabetes later in life.

Obstetric Management:

• Multidisciplinary care including anaesthetists, obstetricians, midwives, and pediatricians is crucial.
• Dietary management and exercise are first-line therapies.
• If lifestyle modifications are insufficient, insulin therapy is required.
• Oral hypoglycemic agents (e.g., metformin or glyburide) may be used if insulin is not appropriate.
• Regular blood glucose monitoring (fasting and postprandial) is essential.

Labor and Delivery Considerations:

• Blood sugar levels should be closely monitored during labor, especially if the mother is on insulin therapy, to avoid neonatal hypoglycemia.
• If large-for-gestational-age (LGA) infants are expected, ultrasound estimates of fetal weight should guide delivery planning.
• The risk of shoulder dystocia should be considered, especially with macrosomia.

• General anesthesia (GA) may be required for emergency LSCS if vaginal delivery is not possible.
  • Gastroparesis and an increased risk of aspiration are concerns in diabetic patients.
  • Blunted cardiovascular response to hypoglycemia can occur under GA, requiring half-hourly blood sugar level (BSL) monitoring.
• Neuraxial anesthesia (e.g., epidural) is often preferred.
  • Aggressive pre-anaesthetic volume expansion with a non-dextrose containing balanced salt solution is recommended.
  • Strict aseptic technique is essential as diabetes increases the risk of epidural abscess.

Postpartum Care:

• Postpartum glucose monitoring is vital. Up to 50% of women with gestational diabetes will develop type 2 diabetes later in life.
• Follow-up should include a fasting glucose test or OGTT 6 weeks post-delivery.
• Breastfeeding is encouraged, as it helps regulate blood glucose levels and reduces the risk of type 2 diabetes.

• Expectant management is an option for women with mild gestational diabetes, but they remain at risk for developing coagulopathies and other complications.
• Psychosocial support should be offered, as GDM can be emotionally distressing for mothers and families.

Long-Term Risks:

• Women with gestational diabetes are at increased risk for developing type 2 diabetes, metabolic syndrome, and cardiovascular diseases.
• Children born to mothers with gestational diabetes are at a higher risk of obesity, metabolic syndrome, and diabetes in later life.