Gestational Diabetes



A summary of NICE and SIGN guidelines for diabetes in pregnancy

NICE SIGN
Preconception
  • folic acid 5mg until 12 weeks' gestation
  • only metformin and insulin for glycaemic control
  • ideally HbA1c<6.1% preconception
  • avoid pregnancy if HbA1c>10%
  • folic acid 5mg 3/12 before until 12 weeks' gestation
  • only metformin and insulin for glycaemic control
  • ideally HbA1c<7.0% preconception
  • stop ACE/ARB, statins pre-pregnancy
Diagnosis of gestational diabetes

Risk factors

  • BMI>30
  • previous baby >4.5kg
  • previous GDM
  • 1st degree relative with DM
  • origin India/Pakistan/Bangladesh/black Caribbean/Middle-East

Previous GDM

  • early self-monitoring, or
  • OGTT at 16-18 weeks' gestation, repeat at 28 weeks' gestation if normal

Risk factors only

  • OGTT at 24-28 weeks' gestation

Definition

  • fasting >=7.0 mmol/l
  • 2-hr >=7.8 mmol/l

Risk factors

  • BMI>30
  • previous baby >4.5kg
  • previous GDM
  • 1st degree relative with DM
  • origin India/Pakistan/Bangladesh/black Caribbean/Middle-East

Risk factors only

  • FPG and HBA1c at booking
  • if HbA1c>=6.5% or 2-hr glucose >=11.1 mmol/l, then diagnose type 2 diabetes
  • if HbA1c 6.0-6.4% or FPG 5.1-6.9 mmol/l (or 2-hr glucose 8.6-11.0 mmol/l if OGTT),
    • consider home glucose monitoring
    • and/or repeat OGTT at 24-28 weeks
  • otherwise, OGTT at 24-28 weeks' gestation

Non-high risk

  • FPG recommended in all at 28 weeks' gestation

Definition

  • fasting >=5.1 mmol/l
  • 1-hr >=10.0 mmol/l
  • 2-hr >=8.5 mmol/l
Treatment and targets
  • GDM: lifestyle inc. low GI diet
  • GDM: medication if blood glucose above targets after 1-2 weeks
  • targets:
    • pre-prandial 3.5-5.9 mmol/l
    • 1-hr post-prandial <7.8 mmol/l
  • don't use HbA1c in 2nd and 3rd trimesters
  • drug options include metformin, glibenclamide, regular insulin, aspart, lispro
  • NPH is preferred to determir/glargine
  • GDM: lifestyle inc. low GI diet
  • GDM: medication if 2+ readings per fortnight are at or above...
    • fasting 5.5 mmol/l
    • 7.0 mmol/l at 2-hrs if <35 weeks' gestation
    • 8.0 mmol/l at 2-hrs if 35+ weeks' gestation
    • 9 mmol/l at any time
  • targets:
    • preprandial 4-6 mmol/l
    • 1-hr postprandial <8 mmol/l
    • 2-hr postprandial <7 mmol/l
  • drug options include metformin, glibenclamide, regular insulin, aspart, lispro
  • NPH is preferred to determir/glargine
Follow-up after GDM
  • FPG (not OGTT) at least 6/52 after delivery
  • annual FPG or HbA1c thereafter
  • FPG/OGTT at least 6/52 after delivery
  • annual FPG or HbA1c thereafter