Gestational Diabetes Flashcards

1
Q

Definition of gestational diabetes

A

A condition in which women without pre-existing diabetes exhibit high blood glucose levels during pregnancy. It is caused by reduced insulin sensitivity and generally resolves after birth.

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2
Q

What is the aetiology of GDM

A
  • Normal pregnancy is characterised by progressive insulin resistance and pancreatic beta cell hyperplasia (secondary to effects of human placental lactogen)
  • GDM develops where insulin resistance overcomes pancreatic beta cell ability to maintain normoglycaemia
  • Resistance usually starts to develop in the 2nd trimester and peaks in the 3rd trimester- allows for steady glucose supply to the foetus
  • After delivery, hPL is no longer produced meaning pregnancy-associated insulin resistance disappears normoglycemia
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3
Q

What is the major consequence of GDM

A

Foetal MACROSOMIA, inhibited surfactant production (impaired lung function), increased oxygen consumption due to elevated metabolic rate (can cause foetal hypoxia and metabolic acidosis), increased erythropoiesis and polycythaemia

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4
Q

Risk factors of GDM

A
  • BMI above 30 kg/m2
  • Previous macrosomic baby weighing more than 4.5Kg
  • Previous GDM
  • FHx of diabetes (first-degree relative with diabetes)
  • An ethnicity with a high prevalence of diabetes (black Afro-Caribbean, middle eastern, South Asian)
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5
Q

WHo should be screened for GDM

A

Anyone with risk factors should be screened with an oral glucose tolerance test at 24-28 weeks of gestation. Women with previous GDM should also have an OGTT soon after their booking visit.

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6
Q

Incidence of GDM

A

1-5 in 100 women develop GDM in pregnancy

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7
Q

Complications of GDM

A

The most significant immediate complications of GDM are large for dates foetus and macrosomia (generally accepted as foetal weight >4000g), associated with:
* Increased birthweight
* 10% preterm labour
* Polyhydramnios due to macrosomia
* Shoulder dystocia and birth trauma
* Foetal compromise, foetal distress and sudden foetal death are more common and related to poor control in the third trimester
* CS or instrumental delivery are more common due to foetal compromise and increased foetal size

Longer-term, women are at a 10x increased risk of developing T2DM after pregnancy:
* UTI, wound and endometrial infection are more common
* Pre-existing HTN found in 25% of overt diabetics
* PET is more common

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8
Q

Investigations for GDM

A
  • The 75g 2hr OGTT should be conducted in any woman with risk factors for GDM

For women who have had GDM in a previous pregnancy, offer:
* Early self-monitoring of BG or
* A 75g 2hr OGTT as soon as possible after booking (whether in first or second trimester) and a further 75g 2hr OGTT at 24-28 weeks if the results are normal
* Consider further testing to exclude GDM in women who have the following reagent strip tests during routine antenatal care:
* Glycosuria of 2+ or above on 1 occasion
* Glycosuria of 1+ or above on 2 or more occasions
* May also consider further testing if there is evidence of polyhydramnios or large for dates foetus

GDM can be diagnosed if the woman has either:
* A FBG of 5.6 mmol/L or above
* A 2-hour plasma glucose of 7.8 mmol/L or above
* Women who are diagnosed should be offered a review with the joint diabetes and antenatal care clinic within 1 week. Their primary healthcare team should also be informed
* Offer all pregnant women with diabetes USS monitoring of foetal growth and amniotic fluid volume every 4 weeks from 28 to 36 weeks
* (Foetal wellbeing monitoring is not indicated before 36 weeks unless there is risk of FGR)

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9
Q

Where are women with GDM managed

A
  • Patients are managed in the ‘joint diabetes and antenatal clinic (after review within 1 week, women should be in contact with the clinic **every 1 to 2 weeks **throughout pregnancy)
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10
Q

How should women with GDM be advised

A
  • That good BG control throughout pregnancy will reduce the risk of foetal macrosomia, trauma during birth, induction of labour, neonatal hypoglycaemia and perinatal death
  • That their care will be jointly managed by the doctors and midwives
  • That treatment includes diet and exercise modification, and could involve medications
  • To maintain their CGB below the following target levels, if these are achievable without causing problematic hypoglycaemia:
    o Fasting: 5.3 mmol/litre
    o 1 hour after meals: 7.8 mmol/litre OR 2 hours after meals: 6.4 mmol/litre.
  • To eat a healthy diet during pregnancy, and switch from high to low glycaemic food
  • Refer all women to a dietician and advise to exercise regularly (walking for 30 minutes after a meal)
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11
Q

How should women be managed if glucose targets are not met with diet and exercise alone

A
  • If blood glucose targets are not met with diet and exercise changes within 1 to 2 weeks, offer metformin (can offer insulin if metformin contraindicated)
  • If targets remain unmet, offer concomitant insulin
  • Glibenclamide (a sulfonylurea) is suggested as an option for women who decline insulin or cannot tolerate metformin.
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12
Q

Management of severe GDM

A

For women with GDM with FBG levels> 7.0 mmol/L OR between 6.0-6.9 AND complications such as macrosomia and polyhydramnios, consider:
* Immediate treatment with insulin, with or without metformin AND diet and exercise modification
* Consider rapid-acting insulin analogues (there is impaired awareness of hypoglycaemia in pregnancy)
* Should always have a fast-acting form of glucose available

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13
Q

When should women with GDM test their BG

A
  • Advise pregnant women with GDM who are on a multiple daily insulin injection regimen to test their fasting, pre‑meal, 1‑hour post‑meal and bedtime blood glucose levels daily
  • Advise women with GDM to test their fasting and 1hr post-meal BG levels daily if they are managing with diet and exercise changes alone or oral therapy
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14
Q

When should women with GDM be referred to a nephrologist

A

Consider referral to a nephrologist If (do not use eGFR as a measure of kidney function):
* Serum Cr is 120 micromol/L or more
* Urinary albumin: creatinine ratio is greater than 30 mg/mmol
* Total protein excretion exceeds 0.5 g/day

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15
Q

How does GDM affect steroid and tocolysis use

A
  • Diabetes should not be considered a contraindication to tocolysis or to antenatal steroids for foetal lung maturation-> women with insulin‑treated diabetes who are taking steroids for foetal lung maturation, give additional insulin and monitor closely
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16
Q

How is timing of birth affected by GDM

A
  • Discuss the timing and mode of birth with pregnant women with diabetes during antenatal appointments, especially during the third trimester
  • Women with GDM should give birth no later than 40+6 weeks- can induce or arrange C-section otherwise
  • Consider elective birth before 40 weeks plus 6 days for women with gestational diabetes who have maternal or foetal complications (e.g USS diagnosed macrosomia)
  • Diabetes is NOT a contraindication to VBAC
  • If the woman has general anaesthesia for the birth, monitor blood glucose every 30 minutes from induction of general anaesthesia
  • Monitor capillary plasma glucose every hour during labour and birth for women with diabetes, and maintain it between 4 mmol/litre and 7 mmol/litre
17
Q

Immediate care for babies born to mothers with GDM

A
  • Babies of women with diabetes should stay with their mothers, unless there are complications or abnormal clinical signs
  • Carry out blood glucose testing routinely at 2 to 4 hours after birth in babies of women with diabetes
  • Carry out blood tests for babies with clinical signs of polycythaemia, hyperbilirubinaemia, hypocalcaemia or hypomagnesaemia

Women with diabetes should feed their babies:
* As soon as possible after birth (within 30 minutes) and then
* At frequent intervals (every 2 to 3 hours) until feeding maintains their pre feed capillary plasma glucose levels at a minimum of 2.0 mmol/litre.

Only use additional measures (such as tube feeding or intravenous dextrose) if:
* Capillary plasma glucose values are below 2.0 mmol/litre on 2 consecutive readings despite maximal support for feeding or
* There are abnormal clinical signs
* the baby will not effectively feed orally
* For babies with clinical signs of hypoglycaemia, test blood glucose levels and provide intravenous dextrose as soon as possible

18
Q

Risks to babies born to mothers with GDM

A

Neonatal hypoglycaemia (baby is used to increased glucose supply during pregnancy), polycythaemia, jaundice, congenital heart disease, cardiomyopathy, macrosomia

19
Q

Postnatal care of women with GDM

A
  • Women with GDM should stop blood-glucose lowering therapy IMMEDIATELY after birth
  • Before women who were diagnosed with gestational diabetes are transferred to community care, test their blood glucose to exclude persisting hyperglycaemia
  • Explain risk of future diagnosis and recurrence in future pregnancies

For women who were diagnosed with gestational diabetes and whose blood glucose levels returned to normal after the birth
* Offer lifestyle advice
* Offer a FBG test at 6-13 weeks postnatally
* DO NOT routinely offer a 75g 2hr OGTT

At FBG test:
* Below 6.0 mmol/L- They have a low probability of having diabetes at that moment, should continue with lifestyle modification, need an annual BG test, moderate risk of developing diabetes
* 6.0-6.9 mmol/L- High risk of developing T2DM, offer advice
* 7.0 mmol/L or more- Likely to have type 2 diabetes, offer them a test to confirm this

Offer an annual HbA1c test to women with gestational diabetes who have a negative postnatal test for diabetes