Hyperglycaemia in pregnancy
Gestational Diabetes Mellitus (GDM) is any degree of glucose intolerance first recognized in pregnancy. Diabetes in pregnancy refers to those with pre-existing diabetes, whether dignosed or not.
Signs and symptoms
Screening at first antenatal visit
• Perform screening in all women at the first antenatal clinic attendance if they have:
o BMI > 25 kg/m2
o Previous history of GDM
o Previous big baby
o Poor obstetric history
o Family history of DM
o Known impaired glucose tolerance/impaired fasting glucose or grand multipara.
• Women in early pregnancy with levels of HbA1c≥6.5% or blood glucose levels fasting ≥7.0 mmol/l or two hour ≥11.1 mmol/l which are diagnostic of diabetes should be treated as having pre-existing diabetes.
• Women with intermediate levels of HbA1c 6.0–6.4%, fasting glucose 5.1– 6.9 mmol/l or two hour glucose 8.6–11.0 mmol/l should be assessed to determine the need for immediate home glucose monitoring and, if the diagnosis remains unclear, assessed for gestational diabetes by 75 g oral glucose tolerance test (OGTT) at 24–28 weeks.
Screening later in Pregnancy
• All women with risk factors (see above) should have a 75 g OGTT at 24–28 weeks
• A fasting plasma glucose at 24–28 weeks is recommended in low-risk women
The rapid-acting insulin analogs (lispro and aspart) lower postprandial blood glucose and decrease the risk of nocturnal hypoglycemia. Patients on lispro and aspart prior to conception may continue them during pregnancy. Patients on regular insulin may be switched to lispro or aspart if 1–hour postprandial blood glucose levels are above target and/or the patient is also experiencing pre-meal or nocturnal hypoglycemia.
Postnatal Follow Up
• Women with gestational diabetes should be screened at 6–12 weeks postnatal to ensure return to normal glucose tolerance. Thereafter, a 1–2 yearly follow up is recommended.
• Metformin and glibenclamide may be used even if a woman is breastfeeding.
• Encourage women to breastfeed.
• If retinopathy, check eyes 1 year postpartum
- • All women with pre-gestational diabetes should:
o Be encouraged to achieve excellent glycaemic control using glucose monitoring of both fasting and postprandial values
o Be prescribed high-dose (5mg) pre-pregnancy folate supplementation, continuing up to 12 weeks’ gestation
o Have an eye exam and be informed of the risk of developing and/or progression of diabetic retinopathy o Have a kidney assessment (random urine albumin/creatinine ratio and serum creatinine) and refered if urine protein ≥ 1g.
• A combined health-care team (obstetrician, diabetologist or internist, diabetes educator, pediatrician/neonatologist) is required. Review SMBG, blood pressure and urine protein and ketones by dipstick at each visit and eye examination in each trimester.
• Target glycaemia:
o Preprandial blood glucose 3.5–5.5mmol/L
o Postprandial blood glucose 5–7.5mmol/L
• Lifestyle management is the preferred means of managing gestational diabetes.
• Diet is based around the principles of optimal nutrition and controlled weight gain.
• Exercise can be helpful in lowering BG levels: the most acceptable form of exercise for most women is walking in their normal daily routine.
• Glucose-lowering therapy should be considered in addition to diet where fasting or two hour glucose levels are above target, for example, where two or more values per fortnight are:
o Fasting or preprandial ≥5.5 mmol/L, or two hours postprandial ≥7 mmol/L at ≤35 weeks
o Fasting or preprandial ≥5.5 mmol/L, or two hours postrandial ≥8 mmol/L at >35 weeks, or any postprandial values are >9 mmol/L.
• When pharmacologic treatment of gestational diabetes is indicated, insulin and oral medications are equivalent in efficacy, and either can be an appropriate first-line therapy.
- • Metformin 500 mg twice daily, maximum 2000mg in 2–3 doses
• Glibenclamine 2.5mg once daily to a maximum of 10mg daily
Oral hypoglycamics (except for metiformin and glibenclamide) are contraindicated in pregnancy