Diabetes and GDM

Question 1

Definitions:

Gestational Diabetes

Answer 1

Carbohydrate intolerance diagnosed in pregnancy which may/may not resolve after pregnancy. International consensus(IADPSG):

1. fasting glucose >5.1 mmol/L OR
2. > 10.0 mmol/L at 1h OR >8.5 mmol/L at 2h OGTT(75g glucose)

NICE 2015:

1. FBG >5.6 mmol/L OR
2. > 7.8 mmol/L at 2h OGTT

Question 2

Epidemiology;

1. Pre-existing diabetes
2. Gestational diabetes

Answer 2

1. 1% pregnant women

2. 3.5%(old NICE), 16%(IADPSG)

Question 3

Fetal complications(GDM less affected compared to established diabetics)

Answer 3

1. Macrosomia
   - Dystocia
   - Birth trauma
2. Polyhydraminos
3. Preterm labour
   - 10% established diabetics
4. Congenital 3-4x
   - NTD and cardiac
5. Reduced fetal lung maturity
6. Fetal compromise, fetal distress in labour, sudden fetal death
   - poor 3rd trimester glucose control.

Question 4

Maternal complications(GDM less affected)

Answer 4

1. Insulin requirements increase
2. Hypoglycaemia from attempts to Tx.
3. Ketoacidosis rare
4. Increased risk instrumental and operative delivery
5. Diabetic retinopathy deterioration
6. Diabetic nephropathy(5-10%) assoc with poorer fetal outcomes.
7. UTI/wound/endometrial infection more common
8. Pre-existing HTN in 25% overt diabetics, pre-eclampsia more common
9. Pre-existing IHD worsens.

Question 5

Management:

Answer 5

Consultant-based antenatal care. Delivery with neonatal intensive care facilities available.

Question 6

a) Preconceptual care(IDDM)

Answer 6

Check renal fn., BP, retina. Optimise glucose control, Folic acid 5 mg/d until 12w. Labetalol/methyldopa to substitute antihypertensives

Question 7

b) Monitoring and tx diabetes

Answer 7

• Target HbA1c <7%
• Antenatal visit every 2w until 34w then every week.
• Target home blood glucose monitoring <6 mmol/L
• NICE 2015 targets:
  i) Fasting 5.3
  ii) 1h after meal 7.8
  iii) 2h after meal 6.4
• Might increase dose as pregnancy advances. T2DM may need insulin. Metformin and glibenclamide(alt to metformin) are safe.

Question 8

c) Monitoring fetus

Answer 8

• Detailed anomaly scan at 20w
• Fetal echocardiography
• USS for fetal growth and liquor V
• Umbilical artery Dopppler if pre-eclampsia/IUGR

Question 9

d) Monitoring for diabetic complications

Answer 9

• renal fn.
• retina. Treat retinopathy
• Aspirin 75mg daily from 12w

Question 10

e) Delivery

Answer 10

• Elective delivery at 37-38+6 w
• ‘Sliding scale insulin’ drg labour. Increase insulin dose if steroids used.
• Elective C-section if fetal W>4kg
• Vaginal delivery within labour <12h but C-section if prolonged

Question 11

f) Puerperium

Answer 11

• Neonatal hypoglycaemia common.
• Respiratory distress syndrome although >38w
• Breastfeeding
• Insulin doses back to prepregnant doses

Question 12

Risk factors

Answer 12

1. Previous GDM
2. Previous fetus>4.5kg
3. BMI>30
4. First degree relative w diabetes
5. South Asian/Black Carribean/Middle eastern
6. PCOS
7. Polyhydraminos
8. Persistent glycosuria
9. Prev unexplained stillbirth

Question 13

Screening

Answer 13

• women at risk undergo 24-28w OGTT. If first 5 risk f present at booking, test then.
• if previous GDM, 2h OGTT asap after booking, further test at 24-28w if first test normal.
• FBG at 28w if low risk

Question 14

Management:

Answer 14

1. Glucometer, dietary and exercise advice. If after 2w, >6 pre-meals/>7 2h after meals, next step.
2. oral hypoglycaemics ie metformin. if after 2w, >6 pre-meals/>7 2h after meals, next step.
3. Insulin. Insulin started also in:
   - FBG ≥ 7 at time of Dx.
   - FBG btw 6-6.9 and evidence of fetal complications
4. Postnatal:
   - discontinue insulin
   - OGTT at 3 months.(>50% Dx as diabetic within 10y)