Diabetes in pregnancy - Diabetes melitus

Question 1

Define

Answer 1

Existing diabetes mellitus in pregnant women (i.e. known; so, no signs/symptoms or investigations)

• Hypoglycaemia is more common in pregnancy and is very dangerous

Insulin resistance INCREASES throughout pregnancy (increase dose of metformin or insulin during pregnancy)

o Postnatally, insulin requirements return to normal levels, so insulin should be adjusted accordingly

Question 2

Symptoms

Answer 2

Question 3

Management

Answer 3

Pre-conception counselling is vital (most women do not get this though):

Pre-conception checks -> tell them to use contraception until these are checked!

1. Glucose control must be tight (use a 4-hour diary) – test HbA1c for risk level
2. Measure HbA1c in 2nd and 3rd trimester (risk greater if >48mmol/mol)
3. Renal testing (U&Es, creatinine)
4. BP checks
5. Retina checks (retinopathy needs to be treated before pregnancy begins)
6. Stop any statin use and start high dose folic acid (5mg, OD) until 12w gestation

Pre-conception counselling:

1. Embryogenesis is affected by DM and so miscarriage risk is higher
2. Poor glycaemic control is teratogenic ( midline deformities such as spina bifida)
3. Growth restriction possible (macrosomic babies can still be growth restricted)
4. Stillbirth risk (from baby outgrowing supply ability of the placenta)
5. Polyhydramnios (baby has osmotic diuresis -> cord prolapse & placental abruption)
6. Hypoglycaemic risk for baby after cut cord as loss of glucose and high insulin levels
7. Higher Infection and DKA rate in pregnancy

If mother has high glucose, the glucose passes to the baby and the baby’s pancreas produces insulin (like IGF-1, a growth factor) and so the baby becomes macrosomic (insulin and fragmin are the two molecules that cannot cross the placenta)

o Blood glucose monitoring (test fasting, pre-meal, 1-hour post-meal, and bedtime daily):

• Fasting blood glucose target <5.3mmol/L [4-7mmol/L]
• 1-hour postprandial target <7.8mmol/L
• HbA1c can be used to assess the level of risk in the pregnancy

o Timeline of contacts:

• 12w “booking” checks
• 20w “anomaly” scans
• 28w, 32w, 36w (4-weekly, serial) foetal surveillance
• 37+0 to 38+6w induction or ELCS
• § Every 2w à joint antenatal-diabetes clinics

o IMPORTANT: if antenatal corticosteroids are needed, additional insulin therapy is required to maintain normoglycaemia (often requires admission) – steroids increase glucose release

o Sliding scale insulin and glucose should be commenced in labour (in T1DM and T2DM)