Neonatology - Gestational Diabetes Flashcards
Defintion
Diabetes triggered by pregnancy.
Aetiology
Reduced insulin sensitivity during pregnancy and resolves after birth
Risk factors
Anyone with risk factors should be screened with an oral glucose tolerance test at 24-28 weeks gestation:
- Previous gestational diabetes
- Previous macrosomic baby (≥ 4.5kg)
- BMI > 30
- Ethnic origin (black Caribbean, Middle Eastern and South Asian)
- Family history of diabetes (first-degree relative)
Signs suggestive of gestational diabetes
Large for dates fetus
Polyhydramnios (increased amniotic fluid)
Glucose on urine dipstick
Diagnosis
FIRST LINE + GOLD STANDARD: OGTT
- An OGTT should be performed in the morning after a fast (they can drink plain water). The patient drinks a 75g glucose drink at the start of the test.
- The blood sugar level is measured before the sugar drink (fasting) and then at 2 hours.
Normal results are:
Fasting: < 5.6 mmol/l
At 2 hours: < 7.8 mmol/l
Results higher than these values are used to diagnose gestational diabetes.
TOM TIP: It is really easy to remember the cutoff for gestational diabetes as simply 5 – 6 – 7 – 8.
Treatment
Need 4 weekly ultrasound scans to monitor the feral growth and amniotic fluid volume from 28 to 36 weeks gestation
Initial management:
- Fasting glucose < 7mmol/l = trial of diet and exercise for 1-2 weeks followed by metformin then insulin
- Fasting glucose > 7 mmol/l = start insulin +/- metformin
- Fasting glucose > 6mmol/l + macrosomia (or other complications) = insulin +/- metformin
SECOND LINE = GLIBENCLAMIDE (sulfonylurea) = suggested as an option for women who decline insulin or cannot tolerate metformin
Target levels for women
- Fasting: 5.3 mmol/l
- 1 hour post-meal: 7.8 mmol/l
- 2 hours post-meal: 6.4 mmol/l
- Avoiding levels of 4 mmol/l or below
Complications
A large for dates fetus and macrosomia
- has implications for birth, mainly posing a risk of shoulder dystocia
- longer-term women at higher risk of developing type 2 diabetes after pregnancy
Children at risk of neonatal hypoglycaemia as babies become accustomed to a large supply of glucose during pregnancy and after birth they struggle to maintain the supply they are used to with oral feeding alone.
Pre-existing diabetes
Women with existing diabetes should aim for good glucose control
Take 5mg folic acid from preconception until 12 weeks gestation
Target glucose same as women with gestational diabetes
Women with type 2 diabetes are managed using metformin and insulin + other diabetic medications should be stopped INVESTIGATIONS: Retinopathy screening at 28 weeks gestation (IMPORTANT)
TREATMENT: Planned delivery between 37-38 weeks + 6 weeks for women with pre-existing diabetes with gestational diabetes can give birth up to 40+6).
Sliding-scale insulin regime: considered during labour for women with type 1 diabetes. A dextrose and insulin infusion is titrated for blood sugar levels. Also considered for women with poorly controlled blood sugars with gestational or type 2 diabetes.
Postnatal care
NO PRE-DIABETES:
Diabetes improves immediately after birth - can stop their diabetes medication immediately after birth.
They need to follow up to test their fasting glucose after at least six weeks.
PRE-EXISTING DIABETES:
Women with existing diabetes should lower their insulin doses and be wary of hypoglycaemia in the postnatal period. The insulin sensitivity will increase after birth and with breastfeeding
Babies of mothers with diabetes are at risk of:
- Neonatal hypoglycaemia
- Polycythaemia (raised haemoglobin)
- Jaundice (raised bilirubin)
- Congenital heart disease
- Cardiomyopathy
What do baby checks need to check for in cases of mothers who have gestational diabetes
Babies need close monitoring for neonatal hypoglycaemia, with regular blood glucose checks and frequent feeds.
The aim is to maintain their blood sugar above 2 mmol/l, and if it falls below this, they may need IV dextrose of nasogastric feeding.
