Diabetes in pregnancy Flashcards
Physiological changes in insulin sensitivity in pregnancy?
State of physiological insulin resistance and relative glucose intolerance.
Glucose handling is different: fasting levels of glucose are decreased and serum levels after a meal are increased.
1st trimester: insulin sensitivity increases.
2nd and 3rd: insulin resistance increases.
Why is glucose tolerance decreased in pregnancy?
due to anti-insulin hormones secreted by the placenta (human placental lactogen, glucagon and cortisol)
What happens to insulin production in pregnancy?
Normal women show a doubling of insulin production from the end of the first trimester to the 3rd trimester.
These changes likely underlie the increased insulin requirements of women with diabetes and the development of abnormal glucose tolerance in women with GDM as there is insufficient insulin secretion to make up for the insulin resistance.
Why is there an increased risk of ketoacidosis in pregnancy?
In normal pregnancy, starvation results in early breakdown of triglyceride resulting in the liberation of fatty acids and ketones- therefore there is an increased risk of ketoacidosis
Diagnosis of diabetes outside of pregnancy?
- HbA1c>48 (41-47=impaired glucose tolerance),
random glucose >11.1,
fasting >7.0,
OGTT >11.1.
Impaired glucose tolerance:
fasting <7.0 and OGTT >7.8 but <11.1).
Effect of pregnancy on pre-existing diabetes
- Increased insulin requirement for T1 and T2. Rapid increases often happen between 28-32/40.
- Women with diabetic nephropathy often experience a worsening of nephropathy although this is usually reversed after delivery
- Twofold risk of diabetic retinopathy during pregnancy- related to degree of control and worsening or first presentation of diabetic retinopathy.
- Hypoglycaemia more common in pregnancy due to intensified control, and possible hypo unawareness. Many of the deaths related to diabetes in the UK are due to hypoglycaemia.
- DKA is rare in pregnancy but incidence increases with hyperemesis/infection/steroids
- Women with autonomic neuropathy and gastroparesis often experience a worsening of symptoms
Estimated prevalence of GDM?
approximately 18%
varies across ethnicities and countries.
In the UK the incidence is increased 11 fold in women from India, 8xSEA, 6x arab/Mediterranean, 3x afro-caribbean
Risk factors for GDM
- Previous GDM
- Previous elevated blood glucose level
- Maternal age >40
- Ethnicity: Asian, Indian, Aboriginal, Maori, Pacific islander, middle eastern, non-white African
- Family history of DM
- Pre-pregnancy BMI>30
- Previous macrosomia (>4.5kg or >95th centile)
- PCOS
- Medications: Steroids, antipsychotics
Diagnosis of GDM (RANZCOG guideline)
- Diagnostic criteria: fasting glucose>5.1, 1 hour >10.0, 2 hour >8.5 (IADPSG- NZ = 2hour >9.0, NICE=7.8)
- HbA1c >48 diagnostic of pre-pregnancy diabetes
- Landmark trial: HAPO 2008. Other trials referenced: Crowther et al 2005 and Langdon et al 2009.
NZ guidelines vs IADSPG
- IADPSG recommend early testing in high risk women with diagnostic criteria: Fasting >5.1 (GDM) and >7.0 (diabetes), Random >11.1, HbA1c >48.
- NZ- criteria for HbA1c is >50, if 41-49 lifestyle advice offered with early OGTT.
Evidence that not treating women with HbA1c 41-46 was associated with increased risk of congenital abnormality, shoulder dystocia, PET and perinatal death.
Importance of identifying GDM
- Increased risk of future T2DM therefore allows women to make dietary changes to reduce their risk or be identified earlier so less likely to develop complications
- A small proportion of women who are diagnosed with GDM will have had diabetes pre-dating the pregnancy
- Women with GDM have a higher incidence of macrosomia and adverse pregnancy outcomes than those without GDM. Treatment of GDM reduces these risks.
Antenatal mx of GDM
- Joint medical/obstetric care in pregnancy Evidence suggests that this improves outcomes.
- Recommend nuchal translucency/1st trimester screening
- 16/40: Offer retinal assessment if diabetic retinopathy previously present.
- 20/40: Anatomy scan including assessment of fetal heart
- 28/40: Growth and LV. If GDM diagnosed- pts enter pathway from here.
- 32+36/40: Growth and LV.
• 36/40: Growth and LV. Provide information about:
o Timing, mode and management of birth
o Analgesia and anaesthesia
o Changes to blood glucose lowering therapy during and after birth
o Care of the baby after birth
o Breastfeeding – benefits
o Contraception and follow up
• 37+0-38-6/40 offer IOL if indicated (type 1 or 2 diabetes with no indication for earlier delivery. GDM complicated by LGA/insulin therapy**)
• 38/40 ‘offer tests of fetal wellbeing’
• 39/40- women with uncomplicated GDM to birth no later than 40+6
Labour mx of GDM
- Measure blood glucose hourly when in labour- aim 4-7
* Consider insulin infusion/sliding scale in T1DM or poorly controlled in labour
Maternal and fetal affects of GDM (not specific to pre-existing)
- Linked to increased risk of cardiovascular disease and T2DM, up to 50% in 20 years.
- Children of women who had GDM are more likely to have T2DM and metabolic syndrome/obesity.
- 3rd trimester: FGR, macrosomia and schedule birth to minimise complications
- Increased risk of PET, especially if pre-existing HTN/renal disease. Risk is proportional to HbA1c- each reduction in HbA1c significantly reduces the risk of developing PET.
- Increased risk of infections, especially thrush.
- Caesarean section rate for women with pre-existing diabetes is approximately 65%- partly due to earlier inductions
- LGA babies (>4.5kg or >90th centile) have increased risk of primary caesarean, neonatal hypoglycaemia and other maternal/neonatal morbidity (HAPO).
- Polyhydramnios -> increased risk of PPROM and cord prolapse.
- FGR- particularly in women with vasculopathy
- Still birth
- Increased neonatal morbidity
- Increased RDS
- Delayed breast feeding
- Worsening of diabetic retinopathy
What congenital abnormalities are babies at an increased risk of having?
Congenital heart disease • Transposition of the great arteries • Double outlet right ventricle • VSD • Truncus arteriosus • Tricuspid atresia • PDA
Neural tube defects
• Anencephaly
• Spina bifida
Caudal regression syndrome Small left colon syndrome Cleft palate Vertebral abnormalities Flexion contracture of the limbs Intestinal abnormalities
Potential neonatal complications of diabetes in pregnancy?
Prematurity Macrosomic/LGA • Including birth associated injuries and complications Perinatal hypoxia Respiratory distress Metabolic complications • Hypoglycaemia (routinely test) • Hypocalcaemia (only if sx) • Hypomagnesaemia (only if sx) • Cardiomyopathy (due to increased synthesis and deposition of fat and glycogen in myocardial cells), transient and should resolve
Haematological complications
• Polycythaemia
• Low iron stores
Hyperbilirubinaemia
Post partum recommendations
- Australian study found that significant proportion of women with GDM who were followed up post partum had diabetes or impaired glucose tolerance
- NICE guidelines: fasting plasma glucose 6-13/52 post partum. Offer yearly HbA1c.
- Recurrence: often recurs but women can reduce risk by losing weight
Benefits of metformin
• Metformin in Gestational diabetes study- metformin safe to use.
- Metformin has anti-angiogenic factors and may reduce risks of: miscarriage in PCOS, increase fertility in PCOS, reduce risk of bowel ca, reduce risk of PET (being researched)
• Benefits of metformin:
- lowers blood glucose levels,
- reduces hypertrigyceridaemia,
- vasoactive properties,
- doesn’t increase weight gain.
Meta analysis study showed: - reduction in LGA, - hypoglycaemia, - reduced maternal weight gain - reduced PIH when compared to monotherapy with insulin.
- Initially insulin was promoted as medication of choice in pregnancy however research has shown the benefits of the use of metformin either instead of or with insulin.
- Prevention of T2DM for women with GDM: intensive lifestyle intervention and metformin use can reduce incidence.
Insulin therapy
- Most women are treated with basal bolus regimes using fast acting insulin (Humalog, Novarapid) taken with meals
- No evidence for better control with insulin pump therapy but if women already using this then continue
- Long acting insulin options: detemir and glargine preference. Glargine often divided into BD dosing after 16-20/40
- Insulin should not be stopped in times of intercurrent illness, dose may need to be increased in the event of infection
- Most women with T2DM will require insulin as well as metformin
Timing of delivery
- Evidence that there may be improved outcomes until 39/40 in general population
- Research mainly from cohort studies and evidence is relatively poor
- T1DM and T2DM- peak incidence of stillbirth is between 37-38+6/40. In the presence of additional risk factors or end organ complication (eg neuropathy/nephropathy) consider earlier delivery.
Consider caesarean when macrosomia present in light of Montgomery v larnarkshire case. After 37 and before 40/40- lowest risk of stillbirth before 39/40.
• Gestational diabetes: SB rate increases after 41/40 and is greater than that of women with no GDM.
Could be reduction in shoulder dystocia/CS rates if LGA and induced at 38/40.
GDM with medication- recommend IOL between 38 and 40/40.
For GDM diet- 40-41/40.
Fetal macrosomia- recommend IOL around 37-38/40. If risk of NVD is substantial then can offer CS.
