Diabetes and Pregnancy

Gestational diabetes

  • Placental progesterones and hPL produce insulin resistance in the mother, meaning more nutrients diverted to foetus
  • If mother is insulin resistant before pregnancy, developing further insulin resistance will raise blood glucose too high and result in gestational diabetes

Complications associated with diabetes in pregnancy

T1 and T2DM

  • Congenital malformation
  • Prematurity
  • Intra-uterine growth retardation (IUGR)

Gestational diabetes

  • Macrosomia (>90th centile for size, birth weight >4kg)
    • Maternal hypoglycaemia is transferred across the placenta, resulting in foetal hyperglycaemia
    • This causes foetal hyperinsulinaemia - insulin is a MAJOR growth factor
    • After birth, the baby takes a while to downregulate the hyperinsulinaemia which puts the baby at risk of neonatal hypoglycaemia
    • Problems with delivery
  • Polyhydramnios
  • Interuterine death

Complications in neonate

  • Respiratory distress due to immature lungs
  • Hypoglyaemia/hypocalcaemia → fits
  • CNS defects - anencephaly, spina bifida
  • Skeletal abnormalities - caudal regression syndrome
  • Genital and GI abnormalities - ureteric duplications

Management of diabetes in pregnancy

T1 and T2DM

  • Pre-pregnancy counseling
    • Good sugar control pre conception to limit risk of congenital malformation
  • Folic acid 5mg (not 400ug as in non-DM pregnancy) at least 3 months prior to conception
  • Consider change from tablets to insulin as some T2DM oral medications are contraindicated in pregnacy
  • Regular eye checks (10, 20, 30 weeks gestation) to check for any accelerated retinopathy
  • Avoid ACEi and probably avoid statins
    • For BP use labetalol, nifedipine, methyldopa
  • Start aspirin 150mg at 12 weeks (as in all high risk pregnancies)
    • Reduces the risk of pregnancy-induced hypertension

T1, T2DM and GDM

  • Diabetic diet
  • Aim for good blood sugar control
    • Pre meal <4-5.5 mmol
    • 2 hr post meal <6-6.5 mmol/l
  • Use continuous glucose monitoring
  • Monitor HbA1c
  • Monitor BP
  • Maintian glood blood glucose during labour - IV insulin and IV dextrose

Drug treatment needed during pregnancy

T1DM
  • Insulin
  • May require increased dose
T2DM
  • Metformin
  • Will probably need insulin later
  • If patients are on many drugs for T2DM it is better to convert to insulin prior to pregnancy rather than trying to convert during pregnancy
GDM
  • Lifestyle
  • Metformin
  • May need insulin

Gestational diabetes after birth

  • 6 week post natal fasting glucose or GTT to ensure resolution of DM
  • If the diabetes persists, patient has T2DM
  • <5% of patients with GDM will go on to develop T1DM
    • In thin patients with GDM check GAD antibodies
  • 50% of patients with GDM will develop T2DM 10-15 years after pregnancy
Prevention of diabetes after GDM
  • Keep weight as low as possible
  • Healthy diet e.g. low refined sugar, low saturated fat
  • Aerobic exercise
  • May consider starting on drug treatment at this stage but as evidence for lifestyle changes is stronger this is rarely done
  • Annual fasting glucose