Learning objectives

• Define gestational diabetes
• Describe the complications associated with gestational diabetes
• Management of gestational diabetes

Definition and mechanisms

• Gestational diabetes is diabetes diagnosed for the first time during pregnancy, resulting in hyperglycemia affecting the pregnancy and baby’s health
• It can happen at any stage of pregnancy but most commonly develops in the second or third trimester
• Usually disappears after giving birth
• Occurs when the body cannot produce enough insulin to meet the extra needs in pregnancy 

Signs and symptoms

Gestational diabetes does not usually cause any noticeable signs or symptoms

• Hyperglycemia
• Antenatal glycosuria
• Increased thirst
• More frequent urination
• Dry mouth
• Tiredness
• Blurred eyesight
• Genital itching or thrush

Complications

Maternal

• Gestational hypertension and pre-eclampsia
• Caesarean section
• Gestational diabetes in future pregnancies
• Type 2 diabetes

Fetal

• Excessive birth weight (i.e., >4.1 kg)
• Preterm birth
• Respiratory distress syndrome
• Hypoglycemia or jaundice
• Obesity and type 2 diabetes later in life
• Polyhydramnios
• Stillbirth

Risk factors

• Age >40 years
• Being overweight or obese (BMI >30 kg/m2)
• Prediabetes
• Gestational diabetes during a previous pregnancy
• Polycystic ovary syndrome
• Family history of diabetes
• Previously delivered a baby weighing ≥4.1 kg
• Black, Hispanic, American Indian, and Asian American ethnicity

Treatment

• Control blood glucose levels
  • Changes in diet and being more active to lower blood glucose
  • Medicine (i.e., tablets or insulin injections) if the above does not lower blood glucose enough
• Blood glucose testing kit to monitor the effects of treatment
• Close monitoring during pregnancy and birth to check for any potential complications
• Best to give birth before 41 weeks → induction of labor or caesarean section may be recommended if labor does not start naturally by this time
• Early delivery may also be recommended if there are health concerns for the mother or baby, or if the blood glucose levels are not well controlled

Management

• Goal: Avoid maternal hypoglycemia or hyperglycemia (which can increase the risk of neonatal hypoglycemia), safe management of glycemic control, effective analgesia for labor
• Availability of appropriate equipment to monitor and treat hypoglycemia or hyperglycemia (e.g., glucometer, infusion pumps, 20% glucose) in the delivery units and obstetric theaters 

Variable rate intravenous insulin infusion (VRII) to maintain glycemic control

• Used when the target CBG range is not achieved by modification of the patient’s usual medications
• Glucose-containing substrate fluid alongside the IV insulin infusion to prevent gluconeogenesis, lipolysis, and ketoacidosis
  • 5% glucose in 0.9% saline with premixed 0.15% (20 mmol/L) KCl or 0.30% (40 mmol/L) KCl to reduce the risk of developing hyponatremia
• Continue basal insulin after starting a VRII

See also pre-eclampsia considerations 

See also caesarean section considerations

Prevention

• Eat healthy foods (high in fiber, low in fat and calories)
• Keep active
• Start pregnancy at a healthy weight
• Do not gain more weight than recommended during pregnancy

Suggested reading

• Yap Y, Modi A, Lucas N. The peripartum management of diabetes. BJA Educ. 2020;20(1):5-9.

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