Gestational Diabetes

Question 1

Outline the pathophysiology of gestational DM

Answer 1

Progressive insulin resistance in preg = high vol of insulin needed (30%) = if not met then transient hyperglycaemia

Question 2

List the risk factors of gestational DM

Answer 2

BMI >30

Asian ethnicity

Previous gestational DM

1st degree relative with DM

PCOS

Previous macrosomic baby (>4.5kg)

Question 3

What are the possible fetal complications from gestational DM?

Answer 3

Macrosomia – shoulder dystocia, obstructed/delayed labour, and/or higher rates of instrumental deliveries

Organomegaly (particularly cardiomegaly)

Erythropoiesis (resulting in polycythaemia)

Polyhydramnios = increased BG, increased UO

Increased rates of pre-term delivery

Reduction in pulmonary phospholipids = transient tachypnoea

Question 4

How should gestational DM be investigated?

Answer 4

75g load (rapilose OGTT solution), 16-18w (prev GDM), 26-28w

Dx = fasting 5.1-6.9, 1h >10, 2h >11.1

UHL referral = fasting >5.6, 2h >7.8

Question 5

Outlie the management of gestational DM

Answer 5

= targets: pre-meal <5.3, 1h <7.8, 2h 6.4, USS: dating by 12w, detailed 20w, growth and LV 3 weekly >26w GROW), ANC 1-4 weekly

Diet

Metformin (500mg BD to 1g BD)

Insulin (novorapid before meals, humulin 1 as background dose)

Delivery 39-40+6, complete UHL DM intrapartum care plan

Postnatal = stop ALL treatment

• FBG at 6-13 weeks
• HBA1c at 13 weeks & yearly thereafter (Risk T2DM)

If fasting glucose >7: Immediate insulin (plus or minus metformin) OR If fasting glucose >6 AND there are complications such as macrosomia

Question 6

What congenital abnormalities can occur due to GDM?

Answer 6

Cardiac

• VSD
• Transposition of the great vessels
• Tetralogy of Fallot
• Persistent fetal circulation
• Truncus arteriosus

NTD
- Spina bifida, anencephaly

MS
- Caudal regression / sacral agenesis

Question 7

Outline DKA in pregnancy

Answer 7

Fetal mortality up to 35%

More common in T1DM

Often in 2nd/3rd trimester

Can be ketotic with glucose not that high (12-14)

Path = state of insulin res, insulin requirement more, increased BG therefore increased DKA 2nd/3rd trimester, accelerated starvation, fetus + placenta use large amount of energy
S+S = N+V

Ix = ketonuria +++, blood ketone >3, BG >11, bicarb (base excess) <15, venous pH <7.3

Mx = DKA protocol in the delivery suite