DIABETES IN PREGNANCY

Why?

Paradigm of medical diseases in pregnancy

Effect of pregnancy on disease Short-term Long-term

Effect of disease on pregnancy Mother vs. fetus Disease vs. its treatment

Prepregnancy vs. gestational

Prepregnancy diabetes

Approximate prevalence 0.5% Increasing In Australia 75% type 1, 25% type 2 Varies with ethnic mix

Effect of pregnancy on diabetesShort-term

Pregnancy is diabetogenic HPL, progesterone antagonize insulin Glucose is major energy substrate for

fetus Pregnancy causes insulin resistance

Insulin requirements in pregnancy

0

50

100

150

200

%

0 4 8 12 16 20 24 28 32 36 40 41 42

Weeks

Effect of pregnancy on diabetesLong-term effects

Nephropathy None if mild-moderate If severe (creatinine > 0.25 mmol/L), may

exacerbate renal failure Retinopathy

Seems to make it worse, but probably due to tight control (DCCT)

Effects of diabetes on pregnancy

Treatment OHAs rarely used

Sulphonylureas ?teratogenic Troglitazone hepatotoxic Acarbose not effective, side effects Metformin ok, but rarely adequate

Insulin Only problem if too much or not enough!

Maternal complications of diabetes

Miscarriage Polyhydramnios Preeclampsia (more if diabetic

nephropathy) Infection (UTI, candidiasis,

chorioamnionitis) Operative delivery (CS rate 50%) PPH

Fetal complications of diabetes

Miscarriage Congenital Malformations

2 - 3 times background rate

minimized by good control around the time or conception and organogenesis

commonest are neural tube and cardiac defects

Caudal regression (sacral agenesis) rare

Perinatal Death Late “unexpected” FDIU

perinatal mortality rate doubled

Neonatal effects of maternal diabetes (IDM)

Macrosomia (40%) Birth trauma Hypoglycaemia Hypocalcaemia/magnesaemia Respiratory distress syndrome Hypertrophic Obstructive CardioMyopathy (HOCM) Hyperbilirubinaemia Hyperviscosity/ polycythaemia The risk of type 1 diabetes mellitus in the child of

a woman with the condition is 2%.

Prepregnancy counselling

Education about diabetes and pregnancy Investigation for complications of diabetes

Microalbuminuria, ophthalmoscopy Optimize glycaemic control

Excellent control minimizes congenital anomalies Switch OHA to insulin HbA1c

Importance of fetal surveillance Lifestyle disruption Folic acid Rubella

Management in pregnancy

TEAM APPROACH Unified clinic Obstetrician, endocrinologist, diabetes

educator, dietitian, neonatal paediatrician (itfot)

Increased frequency of visits 4-weekly to 20 weeks 2-weekly to 28 weeks Weekly thereafter

First visit

Routine management PLUS Repeat prepregnancy counselling steps Urinary protein/ microalbumin excretion Ophthalmoscopy each trimester Glycaemic control Organize fetal surveillance

Glycaemic control

Home blood glucose monitoring qid Goals are 5.5 mmol/L fasting and 7 mmol/L 2

hours postprandial HbA1c monthly Dietary management

Appropriate energy intake 50-60% CHO, 25% fat, 15% protein Even distribution

Exercise - 30 minutes walk a day Insulin

Basal-bolus: 1 dose medium-long acting insulin (e.g. isophane), short-acting with each meal

Hypo management

Fetal surveillance

Ultrasound 12 weeks

gross morphology, dates, plurality, nuchal translucency 18-20 weeks

detailed morphology 30 and 34 weeks

growth Other scans, Dopplers as indicated

Prevention of FDIU CTG weekly from 30 weeks, 2/week from 36 weeks

Timing and route of delivery

RCT suggests advantage in delivery at 38 - 39 weeks Decreased macrosomia, shoulder dystocia 40 weeks if perfect control, no complications

?Role of elective CS for macrosomia Diabetes is independent risk factor for

shoulder dystocia Recommend if estimated fetal weight > 4.5

kg Consider if EFW 4 - 4.5 kg

Management in labour1. Glycaemic control

Notify endocrinologist Omit morning insulin the day of induction. Measure blood glucose on admission and every

2 hours. 50 U insulin in 50 mL 0.9% NaCl (1U/mL) via

syringe pump Start at 1mL/hour Adjust to keep glucose 4-7 mmol/L Simultaneous 5% dextrose at 100 mL/hour

Management in labour2. Obstetric considerations

Usual obstetric management PLUS Continuous CTG Epidural analgesia is encouraged End should be in sight in 12 hours 2nd Stage - Anticipate Shoulder Dystocia Experienced accouchouer and paediatrician must be

present. Prepare to re-position patient (over edge of bed and

exaggerated lithotomy) Active Management of 3rd Stage If elective CS, do first on list

Puerperium

Cease insulin infusion at delivery (unless Caesarean section)

Often reduced needs for 24 hours Then back to prepregnancy dose Type 2 may need no treatment in

puerperium OHAs discouraged in lactation

GESTATIONAL DIABETES

What is gestational diabetes?

Carbohydrate intolerance of varying severity first manifest or diagnosed in pregnancy

The definition applies irrespective of the need for insulin treatment and the result of any postnatal glucose tolerance test

Why gestational diabetes?

Was noted that women with diabetes in pregnancy had high perinatal mortality rate without treatment

This sometimes preceded recognition of diabetes

Pregnancies also characterized by fetal macrosomia

Pregnancy is diabetogenic

Hypothesis

Pregnancy can induce a temporary hyperglycaemic state in susceptible women

This can lead to the typical sequelae of diabetes in pregnancy Macrosomia, preeclampsia, perinatal

mortality Recognition and treatment of these

women can avert these problems Marker for later development of

diabetes mellitus

Diagnosis

Test of carbohydrate metabolism at 24 - 28 weeks in all pregnant women Earlier if high-risk, esp. previous GDM

Most convenient is glucose tolerance test Fasting glucose, 75 g load, 2-hour glucose GDM = fasting 5.5 mmol/L OR 2-hour 8.0

mmol/L Sometimes preceded by glucose

challenge test Non-fasting 75 g glucose load, 1-hour blood

glucose Positive test 8.0 mmol/L leads to GTT

Treatment

Some individual variation, but 3 key elements

1. Achieve normoglycaemia2. Monitor fetal well-being3. Appropriate timing of delivery

Achieve normoglycaemia

Monitor blood glucose Aim for fasting < 5.5 mmol/L and 2-hour

postprandial < 6.5 - 7 mmol/L Initiate carbohydrate modified diet with

balanced intake during day Exercise - 30 minutes walk per day Insulin as required in 25%

Usually 1-2 doses per day sufficient

Ensure fetal well-being

Timing of investigations variable Most perform some test in late pregnancy Commonest test is CTG Start 30 - 36 weeks depending on other

features Ultrasound to determine fetal size

Timing of delivery

If well-controlled, not on insulin, no other problems, deliver at term

Recommend elective Caesarean section if estimated fetal weight > 4.5 kg

Consider if EFW 4 - 4.5 kg If suspected macrosomia, poor control,

deliver at 38 weeks

Management in labour

If not on insulin, usual management + 4-hourly blood glucose Notify if > 7mmol/L

If on low-dose insulin (< 20 U/day) may not need any

If on higher-dose insulin, insulin and glucose infusions as for prepregnancy diabetes 50 U insulin in 50 mL 0.9% NaCl Start at 1mL/hour Adjust to keep glucose 4-7 mmol/L Simultaneous 5% dextrose at 100 mL/hour

Management at delivery

Prepare for shoulder dystocia Cease insulin if used at delivery Monitor infant’s blood glucose after

delivery Measure mother’s blood glucose BD for 2

days

Long-term management

Recall at 6 weeks postpartum for GTT 2% will have diabetes 10% will have IGT

Long-term risk of diabetes mellitus 50% over 10 years

Long-term follow-up Lifestyle modification 50% recurrence in future pregnancy