Diabetes in pregnancy

Definition

• Diabetes mellitus diagnosed during pregnancy

Pathophysiology

• Increased insulin resistance during second and third trimester due to human placental lactogen release from the placenta, among other hormones and inflammatory markers

Epidemiology

• 5.6% in Canada
• 8-18% in Aboriginal people

Risk Factors

• Age >35
• Non-white ethnicity
• History of GDM or IGT
• Obesity
• PCOS
• Macrosomia or twins
• Family history of diabetes
• Current steroid use

Screening

• 50g oral glucose challenge test at 28 weeks
  • If ≥11.1, diagnosed with GDM
  • If ≥7.8, then needs 75g oral glucose tolerance test (OGTT) to diagnose GDM
• Alternate approach
  • No GCT, go straight to OGTT
  • Fasting ≥5.1
  • 1h ≥10
  • 2h ≥8.5

Clinical Presentation

• History
• Signs & Symptoms

Investigations

• Labs
• Imaging
• Other

Management

• Diabetic diet
• Regular moderate exercise
• Self-monitoring of blood sugars including fasting and post-prandial
• Targets
  • Fasting <5.3
  • 1h <7.8
  • 2h <6.7
• Prefer insulin
• Need to prevent neonatal hypoglycemia
• POCT q1h, target 4-7
• Halve insulin as soon as delivery, and continue to check q1h for four hours
• Breastfeeding decreases risk of diabetes
  • Can use metformin, potentially sulfonylurea (but causes macrosomia)
  • Probably shouldn't use DPP-4 inhibitors or GLP-1 agonists, or SGLT2 inhibitors
  • Avoid ACE inhibitors and statins
  • Labour and delivery

Prognosis

• Fetal/Infant
  • Macrosomia
  • Neonatal hypoglycemia
  • Hyperbilirubinemia because lungs and liver are immature
  • Respiratory distress syndrome (for same)
  • Polycythemia
  • Heart defects, sacral agenesis, in preexisting diabetes
  • Shoulder dystocia and brachial plexus injury
• Maternal
  • Long-term risk of obesity and diabetes
  • Operative delivery
  • Hypertension and preeclampsia
  • Diabetes (5x risk)