Overview

• Diabetes Mellitus → existing DM in pregnant woman.
  • Insulin resistance increases throughout pregnancy.
  • Hypoglycaemia is more common in pregnancy.
• Gestational Diabetes → new-onset diabetes during pregancy. Usually occurs at 24-28 weeks gestation. Complications to a lesser degree to normal DM.
  • Risk Factors → BMI >30, previous macrosomic baby (≥4.5kg), south asian ethnicity, FHx of diabetes, previous GDM.
    • If RF’s present → OGTT at 24-28 weeks.
  • Longer term, women at higher risk of developing T2DM after pregnancy.

Making Diagnosis

Clinical Features

• Diabetes Mellitus ⇒
  • Effect of Pregnancy on Diabetes → N&V, greater importance of tight glucose control, increase in insulin dose requirements in 2nd half of pregnancy, increased risk of severe hyperglycaemia, risk of deterioration of any retinopathy/nephropathy.
  • Effect of Diabetes on Pregnancy → increased risk of miscarriage, risk of congenital malformation (spina bifida), risk of macrosomia, increased risk of pre-eclampsia, increased risk of stillbirth, increased risk of infection, polyhydramnios, IUGR, increased operative delivery rate.
    • Macrosomia → greater risk of shoulder dystocia.

Investigations

• Gestational Diabetes (indications for OGTT) ⇒
  • Glycosuria on urine dipstick → immediate 2-hour 75g OGTT.
  • Previous GDM → immediate 2-hour 75g OGTT, if normal then do again at 24-28 weeks.
  • Any risk factors present on clerking → 2-hour 75g OGTT at 24-28 weeks.
• Diagnosis if ⇒ (”5,6,7,8”)
  • Fasting plasma glucose >5.6 mmol/L.
  • 2-hour OGTT >7.8 mmol/L.

Management Plan

• Pre-Conception [DM] → high dose folic acid (5mg) until 12 weeks gestation.

• Antenatal Care ⇒

  • Review at joint diabetes and antenatal clinic within 1 week.
  • Teach self-monitoring of glucose.
  • Serial growth scans every 4 weeks from 28-36 weeks gestation.

• Medical Treatment ⇒

  • 1st Line (only if fasting blood glucose <7 mmol/L) → changes in diet and exercise (2 wk trial).
    • 2nd Line (if targets not met by 1st line in 2 weeks) → metformin.
      • Targets → fasting: 5.3mmol/l, 1 hour post-meal: 7.8mmol/l, 2 hours post-meal: 6.4mmol/l.
  • 3rd Line (if 2nd line ineffective or >7 mmol/L) → add insulin (short-acting).

  <aside> 💡 If fasting blood glucose >7 mmol/L → go straight to Insulin treatment and review in 1 week.

  </aside>

• Intrapartum ⇒

  • Patients with GDM should not give birth later than 40+6 due to increased risk of stillbirth → if necessary induce before this point.
    • Women with T1/2DM should be offered induction or elective Caesarean section, according to the specifics of each case, between 37+0 and 38+6 weeks gestation due to increased risk of stillbirth closer to term.
  • Variable-rate insulin infusion during labour. (If patient was not already on insulin prior to this, do not need this).

• Postnatal Care ⇒

  • Stop diabetic medications immediately after birth. GP follow-up in 6 weeks to test fasting glucose. (50% chance of developing subsequent T2DM).
  • Babies need close monitoring for neonatal hypoglycaemia.
  • Existing Diabetics → immediately reduce their insulin and monitor their blood glucose to establish the most appropriate dose (avoid risk of hypoglycaemia post-partum).

• Subsequent Pregnancies → offer early OGTT (at booking).