FRCA Notes

Gestational diabetes

Resources

  • Diabetes during pregnancy may arise from pre-existing diabetes (0.3%) or de novo (2%)
  • There's a higher risk of GDM in those with previous GDM, a family history of diabetes or those of older maternal age

Before 20 weeks

  • Increased pancreatic insulin secretion owing to the effect of oestrogen
  • Subsequent:
    • Reduced insulin requirements in existing diabetics
    • Lower plasma glucose
    • Increased risk of hypoglycaemia

20 - 40 weeks

  • Insulin resistance develops (owing to the effects of prolactin, cortisol, progesterone and human placental lactogen)
  • A failure of insulin secretion to increase in order to meet demand will lead to GDM
  • Subsequent:
    • Increased insulin requirements (+30%) in existing diabetics
    • Overall hyperglycaemia and risk of DKA
    • Night-time hypoglycaemia as term nears is common, requiring reduced evening insulin doses

Ante-natal

  • Optimisation of diabetic control is vital
  • Poor diabetic control is associated with a number of complications (see below)
  • Management involves dietary changes, metformin and insulin

Complications

Patient factors
Foetal congenital abnormalities, particularly cardiac and renal defects
Perinatal mortality (5x higher)
Foetal macrosomia and its sequelae e.g. shoulder dystocia, need for LSCS, PPH
Higher incidence of PET
Higher incidence of maternal sepsis
Pre-term labour
DKA

Peri-partum

  • VRII may be required
  • If elective LSCS; first on list after omitting morning insulin

  • DKA in pregnancy is associated with a high maternal and perinatal death rate
  • It may be the first presentation of GDM and is an obstetric emergency
  • Incidence of DKA in pregnancy 6.3/100,000
  • According to MBBRACE reports, 90% of patients with DKA during pregnancy could have received better care
  • DKA can occur with lower glucose levels in the presence of raised ketones (euglycaemic ketoacidosis)
    • Abnormally raised ketones should prompt capillary glucose testing and exclusion of DKA