Diabetes in Pregnancy for Undergraduates Max Brinsmead MB BS PhD May 2015

Types and Incidence KNOWN DIABETIC (Before pregnancy) Insulin dependent – Type 1 or Juvenile Onset Diabetes NIDM – Type 2 or Maturity Onset Diabetic Together account for <1% of pregnancies GESTATIONAL DIABETES Diagnosed during a pregnancy May or may not resolve after pregnancy Comprise 2 – 9% of pregnancies depending on the population

Glucose Metabolism in Pregnancy Pregnancy is a diabetogenic stress Results from antagonism of insulin by placental hormones HPL, Sex steroids and corticosteroids The diabetogenic stress increases as pregnancy advances But reverses quickly after placenta delivers BUT… Facilitated transfer of glucose to the parasitic fetus  fasting hypoglycaemia

The Effect of Diabetes on Pregnancy  Maternal blood sugar will  Fetal blood sugar and…  Fetal insulin This causes…  Fetal growth which  Dystocia  Caesarean or shoulder difficulties  Brachial plexus palsy BUT Fetal brain growth is reduced Lung maturation is delayed And the neonate is at risk of hypoglycaemia & hypocalcaemia

Effect of Diabetes on Pregnancy (2)  Fetal blood sugar will cause  Fetal glycosuria  Polyhydramnios There is  risk of intrauterine death ?due to hypoxia ?due to ketoacidosis There is  Rate of maternal Pre eclampsia ?due to placental bed vasculopathy There are  Risks of Prematurity Some of which is due to intervention on behalf of the mother

Extra Risks for Type 1 Diabetics First trimester hyperglycaemia causes…  Rates of congenital malformation (CNS & Heart) If there is diabetic vasculopathy then the inevitable kidney damages causes…  Rates of pre eclampsia  Risk of fetal growth retardation

The Effect of Pregnancy on Diabetes Insulin antagonism   Insulin requirements Pregnancy is a state of lipidolysis so IDDM patients are at  risk of ketoacidosis Especially during labour Will be complicated by nausea, vomiting & slow gastric emptying And altering energy expenditure A desire for tight glucose control and a parasitic fetus puts the mother at risk of serious hypoglycaemia Retinopathy and nephropathy may deteriorate rapidly Insulin requirements change rapidly after delivery

Principles of Management Family Planning Preconception care Stringent blood glucose control before pregnancy Monitor HBA1c Meticulous blood glucose control throughout pregnancy Multidisciplinary care from Physician, Dietition, Nurse Educator and Obstetrician Watch for known complications Timely delivery Appropriate mode of delivery Family Planning

Controversies in Gestational Diabetes Selective or universal testing At least 50% missed unless all screened Glucose challenge or GTT 75G one hour test is best for screening International Group Physicians recommends universal 1-step testing with 75g 2 hr test Criteria for diagnosis Criteria for the use of insulin

Criteria for Selective Testing First degree affected relative Age >35 years Ethnic origin Obesity BMI >30 Poor obstetric history esp. “unexplained stillbirth” Previous fetal macrosomia (>4.5Kg) Clinical suspicion Polyhydramnios Macrosomia Previous Gestational Diabetes

Criteria for the Diagnosis May begin with Fasting and 2 hr Postprandial GLUC If Fasting >7.8 or 2 hr PP >11.0 then… This patient requires insulin ASAP Best test is the WHO 75G 2 hr GTT Diabetes is Fasting GLUC >5.4 or… 2 hr PP >7.8

Management of Gestational Diabetes Diet Abstinence from all simple sugars Reduce fats and oils Regular meals with complex CHO (low glycaemic index) Exercise Self-tested blood glucose 4x  once daily Aim for Fasting GLUC <5.0 And 2 hr PP <6.5 Metformin or Insulin if targets not met Cease any insulin at delivery Repeat 75g GTT after 8 – 12 weeks

Role for Oral Hypoglycaemics Use Metformin or Glibenclamide Achieves the same outcomes as insulin if target GLUC are met Better than insulin at controlling maternal weight 7 – 46% will go on to require insulin

Management of Insulin Dependent Diabetes Before Pregnancy Normalise HBa1c Folic acid 5 mg daily Check kidney and retina Multidisciplinay care Self-tested blood glucose 4x daily Aim for Fasting GLUC <5.0 And 2 hr PP 5.9 – 6.4 Prenatal diagnosis 1st trimester screening by serum biochemistry + ultrasound Routine morphology at 18w Cardiac ultrasound at 22w Scan for growth and umbilical Dopplers 28 & 36w

Delivery of the Pregnant Diabetic Timing for Type 1 diabetics is often a juggle between difficult sugar control and fetal maturity Low threshold for Caesarean especially if fetal macrosomia is suspect Most gestational diabetics induced at term i.e. >37 completed weeks Monitor GLUC in labour May require dextrose and insulin by infusion for those who are insulin-dependant Monitor the fetus in labour

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