Diabetes in pregnancy - Gestational diabetes

Question 1

Define

Answer 1

New-onset diabetes during pregnancy (usually disappears after birth; occurs 24-28w gestation)

· Complications are the same as DM in pregnancy but to a lesser degree (as effects of glucose occur for less time)

GESTATIONAL DIABETES CUT OFFS:

• Fasting plasma glucose ≥ 5.6mmol/L

OR

• 2-hour plasma glucose ≥ 7.8mmol/L

 

Question 2

Aetiology

Answer 2

In normal pregnancy, there is increased insulin resistance as placenta produces human placental lactogen (HPL) which plays a key role in maternal insulin resistance - cause a decrease in insulin sensitivity

• This is because the baby wants more glucose
• Hence if the glucose levels drop quickly all of a sudden you are worried as this may indicate placental insufficiency

In most women, the pancreatic b-cells will be able to compensate for the increased insulin demands to maintain normoglycaemia

Women who develop GDM will have a deficient b-cell response, leading to INSUFFICIENT INSULIN SECRETION to compensate for the increased insulin demands.

NOTE: insulin resistance is most marked in the third trimester, which is why screening is carried out at this point.

Imp as teratogenic for baby

Hyperinsulinaemia also affects surfactant production → impaired lung development

Increased fetal metabolic rate can lead to increased oxygen consumption → fetal hypoxemia → metabolic acidosis

Question 3

Risk factors

Answer 3

BMI > 30kg/m2

Previous macrosomic baby weighing ≥ 4.5kg

Previous GDM

Family history of diabetes (first degree relative)

Family origin with high prevalence of diabetes

• South Asian
• Black Caribbean
• Middle Eastern

Patient may adhere to poor diet (high glycaemic index)- ask!!

Question 4

Symptoms and Signs

Answer 4

Presenting Symptoms

• Usually asymptomatic
• Polyuria
• Polydipsia
• Nocturia
• Weight gain/ loss
• Tiredness/ fatigue

 

Signs O/E

• Elevated BMI
• Foetal macrosomia
• Polyhydramnios/ large for dates

Question 5

Investigations

Answer 5

RISK ASSESS for RISK FACTORS - clinical history

Basic observations

Urine dipstick - booking

Random Glucose- Booking appointment

• < 7.8- normal
• ≥ 7.8 - abnormal –> OGTT

Glucose Challenge Test (1hour GTT)- between 24-28 weeks - another mini screening test using 17 glucose tablets - only done at chelsea

• Fast for 1 hr
• 50g of sugar
• Fast for another hr
• Then measure glucose
• If >7.8 then do OGTT

OGTT

Offered if you have any risk factors bet 24 and 28 wks

• women who’ve previously had gestational diabetes, OGTT should be performed as soon as possible after booking and at 24-28 weeks if the first test is normal.

Diagnostic

• Fast 8-12hrs
• 75g glucose load
• Blood sugar measured 2 hours after

Fasting: ≥ 5.6 = GDM

2 hours: ≥ 7.8 = GDM

HbA1c- measures the average blood glucose concentration over the last 3 months

• Levels < 6% are considered good glycaemic control
• This is used for pre-pregnancy counselling to measure control

Question 6

Management

Answer 6

At DIAGNOSIS:

• If FPG < 7.0mmol/L: conservative, review in 2 weeks à+/- metformin
• If FPG > 7.0mmol/L: conservative + insulin (or if > 6.0 + complications)

Make sure to do prepreg counselling for T1 and T2

1st line (only if fasting blood glucose <7mmol/L): Changes in Diet and Exercise (CDE) [2 weeks trial]

• Refer to dietician (change to low glycaemic index foods)
• Regular exercise (e.g. walking 30 mins after a meal)

2nd line (if targets are not met by 1st line in 2 weeks and <7mmol/L): metformin, CDE

• If metformin is contraindicated/unacceptable, go straight for insulin

3rd line (if 2nd line ineffective OR >7mmol/L or 6.0-6.9mmol/L with complications): insulin, metformin, CDE

• Offer insulin ALONE straight away if… >7mmol/L -> just insulin
• fasting glucose at diagnosis >7mmol/L 3rd line -> insulin, metformin and CDE
• fasting glucose at diagnosis is 6.0-6.9 mmol/L with complications (e.g. macrosomia)

4th line – consider glibenclamide

• In those that metformin does not work but decline insulin; or
• Cannot tolerate metformin (SEs: decreased appetite, diarrhoea, abdominal pain)

Blood glucose monitoring daily = test fasting, pre-meal*, 1-hour post-meal and bedtime*: *if insulin used

• Pre-meal/fasting 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 (not routinely used though)

Question 7

Delivery with Diabetes

Answer 7

PLANNING BIRTH

• T1DM/ T2DM and NO other complications- offer induction of labour or C-section- 37+0 – 38+6 weeks
• T1DM/T2DM and metabolic or maternal/ foetal complications- consider elective birth < 37+0 weeks
• GDM- should deliver no later than 40+6 weeks (by either IoL or C-section)

INTRAPARTUM

• Monitor capillary plasma glucose every hour
• Should maintain between 4-7mmol/L
• If GA is used, monitor capillary plasma glucose every 30 minutes
• IV dextrose and insulin infusion should be considered if:
  
  • T1DM
  • CPG NOT maintained between 4-7mmol/L

T1DM/ T2DM and on insulin- requires an insulin sliding scale to maintain CPG levels

 

POSTPARTUM

• STOP blood glucose-lowering therapy immediately after birth

Post-partum -> GP should perform a fasting plasma glucose at 6-13w post-partum (i.e. at 6w post-natal check)

• <6.0mmol/L à low probability of diabetes, need an annual test, moderate risk of developing T2DM
• 6.0-6.9mmol/L à high risk of T2DM
• >7.0mmol/L à 50% chance of having/developing T2DM à offer diagnostic test to confir

Question 8

Complications

Answer 8

Maternal risks

Pre-eclampsia if have microvascular complications

Renal impairment

Polyhydramnios

• Due to foetal hyperglycaemia, foetus has osmotic diuresis

Risk of infection

Increased risk of PPH

The mother will be at increased risk of developing T2DM later in life (if not pre-existing)

Foetal risks

Neonatal hypoglycaemia with hyperinsulinaemia post-delivery

• Hence baby is checked for blood glucose every few hours
• Need to feed baby early and frequently

Polycythaemia- prolonged neonatal jaundice

• this is due to chronic intrauterine hypoxemia and placental insufficiency secondary to poor glycemic control

Macrosomia or FGR

• Due to foetal hyperglycaemia -> foetal hyperinsulinaemia -> more glucose uptake -> macrosomia
• Good indication of how well controlled the DM is as a met environ not that great is more likely to cause macrosomia

Foetal injuries at delivery- shoulder dystocia

Resp distress (effect on hyperinsulinemia on lung development)

Stillbirth

• Due to foetal hyperglycaemia
• More to do with pre existing T1 and T2

HypoCa, HypoMg, hyperbili Post birth

Question 9

Prognosis

Answer 9

Those with GDM are most likely to have it in future pregnancies but having a healthy weight, eating a balanced diet and taking regular physical exercise before you become pregnant can reduce your risk of developing gestational diabetes again.

The majority of women with GDM will most likely go on to develop T2DM in the future so offered to test for this every year

Tight glycaemic control reduces complication rates

Retinopathy can worsen in pregnancy

Question 10

PACES

Answer 10

What is the problem?

• Explain the diagnosis (diabetes that occurs in pregnancy because the body can’t produce enough insulin to meet the demands of carrying a baby)
• Estimated prevalence: 2-3%
• Risk Factors: age, family or personal history, obesity, multiple pregnancy, Asian
• background
• Explain the risks (MATERNAL: hypertensive disease, traumatic delivery, stillbirth;

FOETAL: macrosomia, neonatal hypoglycaemia, congenital abnormalities)

What are we going to do now?

• Explain the importance of regular exercise and a healthy balanced diet
• Walking for 30 minutes after a meal can help with controlling your blood glucose levels. Gestational diabetes usually improves with these changes
• SC Insulin- explain that this will bring the blood sugar level down and explain the
• importance of good glycaemic control
• Explain how to monitor blood glucose (using glucometer)
• Once in the morning, once in the evening and before and one/two hours after every meal

Remainder of antenatal care?

• Need to be seen at a joint diabetes and antenatal clinic within 1 week (and every 2 weeks thereafter)
• Need to have 4 weekly ultrasound growth scans from 28-36 weeks
• Stress importance of diet and measuring cap glucose throughout the day

Delivery/Birth Plans?

• Advise for delivery no later than 40+6 weeks
• Delivery should be Elective C section or induction of labour before 40+6 weeks

Postnatal?

• Baby should be monitored regularly- 2-4 hourly blood glucose monitoring
• Gestational diabetes babies are prone to hypoglycaemia
• Ensure early and frequent feeding of baby to avoid hypoglycaemia
• Explain that medication will be stopped after delivery but that they will be
• followed up to check if glucose problem continues
• There is a risk that you may develop T2DM after this pregnancy, but this is something we can discuss with you after you have given birth → precautions you can take etc

Diabetes UK - gestation diabetes is a good website to look at