Gestational Diabetes

Pre-Conception Advice

(Dr. Wijeratne 2017 Jan)

1. Attain a preconception HbA1c of ≤ 7.0% (if safe)
   • Do not recommend pregnancy with HbA1c > 7.0 (higher risk = higher HbA1c)
2. Optimize Diabetes:
   • Non-Pharmacological: Weight loss, dietary management etc..
   • Metformin is safe (CDA has not yet adopted this)
   • Switch to insulin if on oral agents
3. Folic Acid - 5mg/day (at least 3mo prior to pregnancy to 12w post conception) (just like antiepileptics, hx of NTD)
4. Assess and manage any complications (pregnancy worsens retinopathy/nephropathy)
5. Stop teratogenic meds
   • ACE inhibitors, ARBs
   • Statins

NOTE: DPP4 inhibitors (gliptins) have not been studied, glyburide seems to be safe as an alternative to insulin. 

Diagnosis/Screening

• ALL pegnant women should be screened for GDM 24-28w gestation.
  • (If there is high risk, screen at any stage)
  • If screening @ 24w is negative --> Rescreen 24-28w.
• Risk Factors:
  • Previous diagnosis of GDM
  • Prediabetes
  • High Risk Population (Aboriginal, Hispanic, South Asian, Asian, African)
  • Age >= 35yo
  • BMI >= 30 kg/m2
  • PCSO, acanthosis nigricans
  • Corticosteroid use
  • Fetal Macrosomia or polyhydraminos (current or previous)
• After birth - repeat testing at 6w post-delivery.
• Screening:
  • 50g GCT to non-fasting patient.  Measure PG 1hr later.
  • NOTE: In old test, 75g OGTT (need two values abnormal, but new guidelines: need two abnormal)

    • <7.8 mmol/L	Normal
      7.8 - 11.1 mmol/L	Proceed to 75g test
      >= 11.1 mmol/L	Diabetes

    • • < 7.8 mmol/L --> Normal 
      • 7.8 - 11.1 mmol/L --> FASTING 75g OGGT
        • Fasting   --> 5.3
        • 1 hour Value  --> 10.6
        • 2 hour Value  --> 9
      • >= 11.1 mmol/L = DIAGNOSIS.
• Diagnosis
• 75g OGTT
  • PG 1hr > 10.6
  • PG 2hr > 9
  • Fasting > 5.3

GDM Monitoring

• Monitor:
  • Fasting Blood Glucose
  • 1-hr Post-Meal sugars

• CDA Guidelines Targets: FBG > 5.3 start NPG 4-6u 1-hour Post-meal > 7.8  --> start humalog 4u before the meal with elevation (titrate up).   Delivery Target Target: 4-7  (less than in-hospital targets 5-10 and 8-10 to avoid neonatal hypoglycemia)

POSITIVE OGTT

• 1: Try to control with diet first!
  • Avoid diet in simple sugars
• 2: If unable to keep to targets
  • FBG > 5.3 --> Start insulin 0.1-0.3 u/kg
    • Insulin Glargine is preferred due to slow release
    • Insulin Aspart for mealtime due to low risk of postprandial hypoglycemia