Diabetes in pregnancy

 

  • Results in a high risk pregnancy with complications increased for both mother and baby
  • Adverse (bad) outcomes can be minimised with good diabetes control

Medical conditions with high blood glucose levels

Gestational diabetes mellitus (GDM)

  • High blood glucose first detected in the second half of pregnancy

Early GDM 

  • Likely pre-existing prediabetes
  • High blood glucose first detected before 20 weeks gestation but is below non-pregnant diabetes criteria
  • Increased risk of complications compared to standard GDM

Overt diabetes in pregnancy

  • High glucose first detected in pregnancy but meets non-pregnant criteria for diabetes
  • Treat as pre-existing diabetes during the pregnancy
  • Can only confirm whether or not woman has type 2 diabetes after pregnancy

Pre-existing type 2 or type 1 diabetes

  • Diagnosed before pregnancy

Diagnosis and management of diabetes in pregnancy is important

  • Diabetes in pregnancy is common and increasing in all age groups
    • Affects one in five pregnant Indigenous women
  • Aim to keep BGL at normal levels to reduce complications
  • Multidisciplinary team management is needed — involving primary care, midwife, obstetrician, diabetes educator, dietitian, nurse practitioner and endocrinologist
  • Clear communication and consistency of care between services is important

Table 2.10   Potential complications of diabetes in pregnancy

Pre-pregnancy counselling for women with known diabetes

Optimising health in women with diabetes before pregnancy is needed to reduce risk of complications for both woman and baby

  • Discuss pregnancy planning and contraception at routine check-ups with all women of childbearing age
    • If HbA1c over 9% suggest delaying conception (becoming pregnant) until close to or lower than 7% 
  • Talk about and assist women with
    • Target glucose-levels before pregnancy — HbA1c less than 6.5% without hypoglycaemia will minimise risks to woman and baby
    • Need to optimise BP, weight, nutrition and physical activity
    • Check woman is up-to-date with kidney and diabetes eye checks
  • If planning pregnancy or not using reliable contraception
    • Review medications
    • Start folic acid oral — 5mg once a day  — high dose due to increased risk of congenital anomalies with diabetes
  • Monitor for pregnancy at routine visits. Tell woman to notify clinic as soon as thinks she is pregnant

Screening for diabetes in pregnancy

  • First antenatal visit — screen all pregnant women who are not already known to have diabetes and have risk factors — best before 13 weeks pregnant
    • All Aboriginal women are at high risk — need to test at first antenatal visit
  • 24–28 weeks pregnant — screen or re-screen all pregnant women not already known to have diabetes
  • For tests and interpretation follow Flowchart 2.4

Flowchart 2.4 Screening pathway for women not already known to have diabetes

Blood glucose targets for pre-existing diabetes and GDM
  • Provide all women with glucometer and teach to check BGLs
  • Self-monitoring 4 times per day — fasting and 2-hours after meals
  • Advise to keep BGL diary. Bring diary and meter to each review
  • Review BGL diary weekly — usually by diabetes educator or midwife
    • If BGLs within target — no change in management
    • If 2 or more readings above target in 1 week — review diet, physical activity and medicines
    • If BGLs significantly above target — may need more frequent diabetes educator or medical input for titration of therapy. May be done by telehealth
  • Frequency of BGL self-monitoring can be reduced or increased according to progress
    • If BGLs on target with diet change only and normal foetal growth, reduce testing 
    • If on insulin with meals, test 6 times per day — before and 2-hours after meals

Table 2.11   Monitoring and targets

Antenatal care for pre-existing diabetes

At first antenatal visit

Check

Do

Medical consult — include urgent medicines review

  • Continue metformin and/or insulin if already prescribed
  • Stop medications that are not safe in pregnancy 
    • Other glucose-lowering medicines
    • ACE inhibitor or ARB  — consider safer options for BP control, eg methyldopa, labetalol
    • Statins and other lipid-lowering medicines
  • May need to start insulin

Also

  • Add to first visit routine investigations 
    • Blood for HbA1c, TFT, UEC, B12, Urine ACR
  • Diabetes educator consult. Can use telehealth
  • Give folic acid oral — 5mg once a day until 12 weeks pregnant
  • Give iodine oral — 150microgram once a day. Can be in multivitamin designed for pregnancy and breastfeeding
    • If woman has thyroid condition — medical consult
  • Give advice on diet and physical activity to help control blood glucose — refer to dietitian
  • Start home BGL monitoring
    • give glucometer and consumables including diary and pen
    • Review pre-pregnancy BMI and discuss healthy weight gain targets
  • Arrange as soon as possible
    • Ultrasound scan to date pregnancy, if not already done
    • Obstetric review
    • Endocrinologist/physician review
    • Retinal screening, if not done within 3 months before pregnancy. If retinopathy present — repeat screening each trimester — seek ophthalmology advice for treatment
  • Make sure woman is on recall system to be followed up after birth — see Postpartum follow-up of medical conditions

Additional antenatal care

Additional care is needed because of increased risk of complications

Check

  • Review BGL diary and glucometer every week — see blood glucose targets for pre-existing diabetes and GDM
  • Monitor gestational weight gain — see Healthy weight in pregnancy
  • Extra ultrasounds as ordered by obstetrician — could include
    • Extra ultrasounds for foetal growth in the second and third trimesters
    • Management is individualised and will be advised by the managing obstetrician

Do

  • Once each trimester
    • Blood for UEC, LFT, HbA1c, Urine ACR
  • Strongly encourage testing for foetal abnormalities
  • Education about diabetes in pregnancy
  • Antenatal check every 2 weeks until 28 weeks pregnant
    • THEN every 1 week from 28–36 weeks
  • At 32 week antenatal check — talk to woman about being added to Diabetes in Pregnancy Clinical Registers, if relevant to your jurisdiction
  • Medical follow up as needed — at least every 4 weeks — for adjustment of diabetes medicines
  • Medical consult for routine prevention of risk of preeclampsia
    • Aspirin oral — 100–150mg once a day with evening meal from 12 weeks until 36 weeks gestation
    • Calcium supplementation oral — up to 1.5g once a day including dietary calcium intake from 12 weeks gestation
  • Arrange for transfer to regional centre at 36 weeks to wait for birth — hospital birth

Antenatal care for GDM

At first antenatal visit after diagnosis

Do

  • Routine antenatal check — see Antenatal checklist AND
    • Blood for UEC, LFT, HbA1c, urine ACR
  • Start home blood glucose monitoring
    • Give glucometer and consumables including diary and pen 
    • Teach woman how to self-monitor and keep BGL diary
  • Medical consult
  • Diabetes educator consult — can use telehealth
  • Review pre-pregnancy BMI and discuss healthy weight gain targets
  • Arrange obstetric review as soon as possible
  • Make sure woman on recall system are followed up after birth — see Postpartum follow-up of medical conditions

Additional antenatal care

Additional care needed due to increased risk of complications

Check

  • Review BGL diary and glucometer every week — see blood glucose targets for pre-existing diabetes and GDM 
  • Monitor gestational weight gain — see Healthy weight in pregnancy
  • Ultrasounds as ordered by obstetrician. Could include
    • Extra ultrasounds for foetal growth in the second and third trimesters
    • Management is individualised and will be advised by the managing obstetrician

Do

  • Education about diabetes in pregnancy
  • Antenatal check every 2–4 weeks until 36 weeks pregnant THEN every week from 36 weeks pregnant
    • If on insulin — see every week from 28 weeks
  • At 28 and 36 weeks
    • Blood for UEC, LFT, HbA1c, urine ACR
  • Medical follow up as needed — at least every 4 weeks — for adjustment of diabetes medicine
  • Consider referral to tertiary (major hospital) diabetes service if BGL is often above target or if advice is needed on medical management
  • Arrange for hospital birth — transfer to regional centre at 38 weeks to wait for birth

Education

  • Importance of healthy diet, physical activity, healthy weight gain
  • Complications — reassure that not all women develop complications and looking after GDM helps to keep woman and baby healthy
  • Benefits of keeping BGLs within target range
    • Need to monitor and record own BGL in pregnancy
    • Medicines including insulin might be needed
  • Need for extra checks in pregnancy
  • Hospital birth recommended
    • Baby may also need special care straight after birth
  • Advise which clinic staff will give more support and provide access to educational materials

Medicines for pre-existing diabetes and GDM

  • Must be prescribed by doctor or nurse practitioner
  • Medicines are needed for all women with pre-existing diabetes
  • Medicines must be started in GDM when BGLs are very high or are not within target after dietary changes and physical activity have been trialled briefly (for a week)
  • Choice of medicine must be based on individual woman’s needs — consider preferences, gestation, BGLs and foetal growth
  • Metformin and insulin are safe to use in pregnancy. Other diabetes medicines should not be used

Metformin 

  • Is a treatment option in pregnancy
  • Crosses the placenta but there is no evidence of harm to the baby during pregnancy
  • If woman is on metformin before pregnancy — continue
  • For GDM — medicine options can be discussed
    • Half of women with GDM on metformin will also end up needing insulin
  • Diarrhoea and nausea are common side effects — taking it everyday and after food helps
  • Stop if ultrasounds show foetal growth restriction OR small-for-gestational-age OR if mother has inadequate weight gain if she has a low BMI (underweight)
  • Use standard doses as for non-pregnant woman

Insulin

  • Most women with pre-existing diabetes and about one-third of women with GDM will need insulin
  • Recommended if blood glucose not controlled by diet and exercise or metformin. Continue to review diet in woman taking insulin
  • See Table 2.12 for suggested regimen

Starting and titrating insulin treatment

  • Medical/diabetes educator consult about best insulin regimen — the type of insulin depends on BGL pattern and if it is suitable for that woman 
    • Women needing insulin in pregnancy should be referred to tertiary diabetes service
  • On advice of doctor or nurse practitioner, other clinicians can titrate insulin according to Table 2.12
    • If low or persistent high BGLs — medical consult
    • After each change in insulin dose, monitor BGL for 2 days before making another change

Table 2.12   When and how to start and then titrate insulin

Follow-up