Diabetes in Pregnancy
NICE Guideline NG3 Diabetes in pregnancy: management from preconception to the postnatal period. Last updated: Dec 2020.
This article covers BOTH gestational diabetes and pre-existing diabetes in pregnancy.
Gestational Diabetes Guidelines
Screening
Screening for gestational diabetes is indicated if ANY of the following:
- Previous gestational diabetes
- Previous macrosomic baby (≥4.5 kg)
- 1st degree relative with diabetes mellitus
- Ethnicity with high prevalence of diabetes mellitus
- BMI >30 kg/m2
If glycosuria is detected by routine antenatal testing → consider further testing to exclude gestational diabetes
Testing Timing
If the patient had previous gestational diabetes → offer early testing (at booking appointment)
- Self-monitoring of blood glucose / OGTT
- If early testing is normal → perform standard OGTT at 24-28 weeks
If any other indications (listed above) → offer screening (OGTT) at 24-28 weeks (no need for early testing)
Testing and Diagnostic Criteria
Test of choice: 75g 2-hour OGTT
Diagnostic criteria (either of the following met):
| Test | Cut-off |
|---|---|
| Fasting plasma glucose | ≥5.6 mmol/L |
| 2-hour plasma glucose | ≥7.8 mmol/L |
A way to remember the diagnostic criteria for gestational diabetes is 56,78.
Management During Pregnancy
General Advice / Conservative Management
Newly diagnosed women should be seen in a joint diabetes and antenatal clinic within 1 week
Main purposes of appointment:
- Starting lifestyle intervention
- Changes in diet and regular exercise
- All women referred to dietician
- Initiating self-monitoring of blood glucose (all patients but more frequent monitoring needed if using insulin)
- Starting pharmacological management (if necessary) → see below
Self-Monitoring Blood Glucose Targets
The following targets apply for all pregnant women with diabetes (inc. pre-existing type 1 or 2 diabetes / gestational diabetes)
| Timing | Glucose Target |
|---|---|
| Fasting | <5.3 mmol/L |
| 1 hour after meals | <7.8 mmol/L |
| 2 hours after meals | <6.4 mmol/L |
| All time | >4.0 mmol/L (to prevent hypoglycaemia) |
Extra practical details on frequency of self-monitoring blood glucose in gestational diabetes:
- If the patient uses multiple daily insulin injections → more frequent (fasting, pre-meal, 1 hour post-meal, bedtime glucose daily)
- Otherwise (including using single dose insulin) → less frequent (fasting and 1 hour post-meal glucose daily)
Pharmacological Management
The approach depends on fasting plasma glucose levels
| Scenario | Management |
|---|---|
| Fasting plasma glucose <7.0 mmol/L |
|
| Fasting plasma glucose ≥7.0 mmol/L | Offer the following immediately:
|
| Fasting plasma glucose 6.0-6.9 mmol/L + complications (e.g. macrosomia or hydramnios) | Offer diet and exercise changes
Consider insulin +/- metformin immediately |
Types of insulin that can be used in pregnancy:
- Isophane insulin (also known as NPH insulin) → 1st line long-acting insulin for diabetes in pregnancy (BOTH gestational & pre-existing)
- For pre-existing diabetes: consider continuing insulin detemir or insulin glargine (long-acting insulins) in women who had stable, good glycaemic control on these treatments before pregnancy
- Rapid-acting insulin analogues (aspart and lispro)
Insulin regimens
- NICE does not specify a preferred regimen in pregnancy; management is individualised
- Most women use a basal-bolus regimen with frequent dose titration to meet pregnancy glycaemic targets
- Both multiple daily injections and CSII (insulin pump therapy) are acceptable, with no clear evidence that one is superior [Ref]
Intrapartum care
Give birth in hospitals where advanced neonatal resuscitation skills are available.
In the absence of other complications / indications:
- Gestational diabetes → elective birth before 40+6 weeks
(for uncomplicated pre-existing type I / II diabetes → elective birth between 37-38+6 weeks)
Neonatal Care
Applies for all women with diabetes in pregnancy (inc. pre-existing type 1 and 2 diabetes / GDM)
Detecting and preventing neonatal hypoglycaemia:
- Carry out blood glucose testing routinely at 2-4 hours after birth
- Mother should feed the baby ASAP (within 30 minutes)
- Then, feed at frequent intervals (every 2-3 hours) until maintaining pre-feed capillary blood glucose >2.0 mmol/L
Do not transfer babies of women with diabetes to community care until:
- At least 24 hours old
- Baby is feeding well and maintaining blood glucose levels
Management After Pregnancy
Before Discharge
Perform the following:
- Stop blood glucose‑lowering therapy immediately after birth
- Test for blood glucose (to exclude persisting hyperglycaemia)
After Discharge (Community Care)
Offer the women:
- Lifestyle advice (including weight control, diet and exercise)
- Fasting plasma glucose test at 6-13 weeks after birth (to exclude diabetes)
Subsequent actions depending on fasting glucose level:
| Fasting plasma glucose | Interpretation | Action |
|---|---|---|
| < 6.0 mmol/L | Low probability of current diabetes |
|
| 6.1 – 6.9 mmol/L | High risk of developing type II diabetes | Follow guidance on type II diabetes prevention |
| > 7.0 mmol/L | Likely to have type II diabetes | Work up and treat as type II diabetes |
If post-natal testing for diabetes is -ve → annual HbA1c
In future pregnancies:
- Offer early self-monitoring of blood glucose, OR
- Early OGTT
Pre-existing Diabetes Guidelines
Pre-conception Management
NICE advises using contraception until good blood glucose control.
- Advise women with diabetes who are planning a pregnancy to aim for HbA1c <48 mmol/mol (6.5%)
- Strongly advise NOT to get pregnant if HbA1c >86 mmol/mol (10%), until their HbA1c level is lower
Additional management:
- Individualised dietary advice
- Weight loss if BMI >27 kg/m2
- High-dose folic acid (5mg/day) from planning until 12 weeks of gestation
- Retinal and renal assessment before pregnancy
The following medications should be stopped before pregnancy or as soon as pregnancy is confirmed:
- ALL oral anti-diabetic medications (apart from metformin) → start insulin (rapid-acting insulin analogue preferred)
- ACE-I / A2RB
- Statins
This is not an exhaustive list of medications to stop in pregnancy; these are outlined only because they are often used by diabetic patients.
The only diabetic medications that are safe in pregnancy are:
- Metformin
- Insulin
Patient Counselling
Explain to women that good glucose control before contraception and throughout their pregnancy will reduce risk of:
- Miscarriage
- Congenital malformation
- Stillbirth
- Neonatal death
NICE recommends providing the following information to patients (not exhaustive and expanded):
- Maternal risk:
- Pregnant women are more prone to hypoglycaemia and impaired awareness of hypoglycaemia
- Nausea and vomiting in pregnancy can affect blood glucose control
- Pregnancy may worsen diabetic retinopathy
- Diabetic nephropathy may worsen and increase the risk of pre-eclampsia
- Poor blood glucose control during labour and birth may increase the risk of neonatal hypoglycaemia after birth
- Neonatal risk:
- Macrosomia (increases risk of birth trauma, induction of labour, instrumental and caesarean section deliveries)
- Increased risk of health problems in the first 28 days (e.g. hypoglycaemia, jaundice, respiratory distress)
- Increased risk of developing obesity / type II diabetes in later life
Management During Pregnancy
The following are in addition to standard antenatal care due to pre-existing diabetes
Additional intervention:
- High-dose folic acid (5mg) until 12 weeks (to reduce risk of neural tube defects)
- Aspirin 75-150mg from 12 weeks until birth (to reduce risk of pre-eclampsia)
Additional precautions / monitoring:
- At the booking appointment
- Refer immediately to joint diabetes antenatal clinic
- Perform HbA1c to determine risk of pregnancy (and consider in 2nd and 3rd trimesters)
- Self-monitoring of blood glucose
- Retinal assessment (by digital imaging with mydriasis)
- Renal assessment (do not use eGFR in pregnancy)
- Additional ultrasound monitoring (at 28, 32, 26 weeks) for fetal growth and amniotic fluid volume
Self-Monitoring Blood Glucose
The following targets apply for all women with diabetes in pregnancy (inc. pre-existing type 1 or 2 diabetes / GDM)
| Timing | Glucose Target |
|---|---|
| Fasting | <5.3 mmol/L |
| 1 hour after meals | <7.8 mmol/L |
| 2 hours after meals | <6.4 mmol/L |
| All time | >4.0 mmol/L (to prevent hypoglycaemia) |
Extra practical details on frequency of self-monitoring blood glucose in pre-existing diabetes:
- If type I diabetes → more frequent (fasting, pre-meal, 1 hour post-meal, bedtime glucose daily)
- If type II diabetes on multiple daily insulin injections → more frequent (fasting, pre-meal, 1 hour post-meal, bedtime glucose daily)
- If type II diabetes not using multiple daily insulin injections → less frequent (fasting and 1 hour post-meal glucose daily)
Insulin Treatment During Pregnancy
Types of insulin that can be used in pregnancy:
- Isophane insulin (also known as NPH insulin) → 1st line long-acting insulin for diabetes in pregnancy (BOTH gestational & pre-existing)
- For pre-existing diabetes: consider continuing insulin detemir or insulin glargine (long-acting insulins) in women who had stable, good glycaemic control on these treatments before pregnancy
- Rapid-acting insulin analogues (aspart and lispro)
Insulin regimens
- NICE does not specify a preferred regimen in pregnancy; management is individualised
- Most women use a basal-bolus regimen with frequent dose titration to meet pregnancy glycaemic targets
- Both multiple daily injections and CSII (insulin pump therapy) are acceptable, with no clear evidence that one is superior [Ref]
Additional Management in Type I Diabetes
In addition to the above, also offer:
- Real-time continuous glucose monitoring (rtCGM)
- Alternative: intermittently scanned continuous glucose monitoring (isCGM)
- Blood ketone testing strips and meter
- Advise to test for ketonaemia and seek urgent medical advice if they become hyperglycaemic or unwell
Intrapartum care
Give birth in hospitals where advanced neonatal resuscitation skills are available.
In the absence of other complications / indications:
- Type I / II diabetes → elective birth between 37-38+6 weeks
(If gestational diabetes → elective birth before 40+6 weeks)
Neonatal Care
Applies for all women with diabetes in pregnancy (inc. pre-existing type 1 and 2 diabetes / GDM)
Detecting and preventing neonatal hypoglycaemia:
- Carry out blood glucose testing routinely at 2-4 hours after birth
- Mother should feed the baby ASAP (within 30 minutes)
- Then, feed at frequent intervals (every 2-3 hours) until maintaining pre-feed capillary blood glucose >2.0 mmol/L
Do not transfer babies of women with diabetes to community care until:
- At least 24 hours old
- Baby is feeding well and maintaining blood glucose levels
Management After Pregnancy
Refer back to their routine diabetes care arrangements.
If treated with insulin, reduce insulin immediately after birth and monitor blood glucose to titrate the appropriate dose.
For breastfeeding women:
- Metformin can be continued / resumed
- Avoid ALL other oral blood glucose-lowering therapy while breastfeeding