Diabetes Flashcards
Define gestational diabetes mellitus (GDM)
Carbohydrate intolerance of variable severity with onset or first recognition during the present pregnancy.
What are the plasma glucose cut offs for diagnosing GDM?
Fasting: >5.1 mmol/L
OGTT 1 hr post: >=10.0 mmol/L
OGTT 2 hr post: >8.5 mmol/L
What are the plasma glucose cut offs for diagnosing DM in pregnancy?
Fasting: >= 7.0 mmol/L
*No OGTT 1 hr post criteria.
OGTT 2 hr post: >=11.1 mmol/L
Random: >=11.1 mmol/L
What are the plasma glucose cut offs for diagnosing impaired glucose tolerance?
Fasting: >=6.1 but <7.0 mmol/L
*No OGTT 1 hr post criteria.
OGTT 2 hr post: >=7.8 but <11.1 mmol/L
What congenital malformations are associated with pre-existing DM?
Congenital heart disease
Anencephaly
Microcephaly
Neural tube defects
Sacral agenesis - specific to diabetes, but rare
Directly proprotional to HbA1c during first 10/40
In the first trimester, what maternal risks are present with pre-existing DM?
- Hypogclyaemia (with nausea and vomiting / hyperemesis in pregnancy)
- Impaired hypoglycaemia awareness during pregnancy
- Diabetic ketoacidosis
For women with pre-existing DM, how often should the HbA1c be tested?
At least once a trimester
What are the treatment goals for women with pre-existing DM?
Fasting: 4.0 - 5.3
1 hour: 5.5 - 7.8
2 hours: 5.0 - 6.7
How do insulin requirements change during pregnancy?
Insulin requirements increase steadily through pregnancy - T1DM may need a 2 fold increase in pre-pregnancy insulin; T2DM may require insulin in addition to metformin.
Decline slightly towards term
Small reductions 5-10% are common
HOWEVER, marked decreases > 15% raise concern regarding placental function
- limited evidence
- indication for surveillance rather than delivery
If EFW > 4.5kg with DM, there is a _____ risk of shoulder dystocia
20%
Therefore, consideration should be given to El LSCS
But NNT to prevent one permanent BPI is 443
How are monogenic diabetes disorders inherited?
Autosomal Dominant
Fetus has 50% chance of inheriting it
What are risk factors for developing GDM?
BMI > 30
AMA 40+
Previous GDM
Family history of diabetes (first degree relative with DM or sister with GDM)
Ethnicity: Asian, Indian subcontinent, Aboriginal and Torres Strait Islander, Maori, Pacific Islander, Middle Eastern, non-white African
Previous baby > 4.5kg
PCOS
Medications: corticosteroids, antipsychotics
When should women have diabetes testing in pregnancy, and how?
All women:
- Booking HbA1c
- 75g OGTT at 26-28/40
Women with risk factors:
- early pregnancy OGTT
- repeat OGTT at 24-28 weeks if not diagnosed in early pregnancy
2 step procedure with polycose no longer recommended.
What is the recommended timing of delivery for a woman with T1DM or T2DM
At the latest, 38+6/40
Because after 39/40, risk stillbirth goes up (RR with DM is 7.2)
What are the signs and symptoms of DKA?
Nausea, vomiting Abdominal pain Thirst, dry mouth Reduced urine output Unusual, fruity smelling breath Rapid breathing, dyspnoea Tachycardia, palpitations Drowsiness, confusion, disorientation
What is the Pederson hypothesis?
Maternal hyperglycaemia leads to fetal hyperglycaemia which causes fetal pancreatic ß cells hyperplasia, and increased circulating insulin.
Insulin is an anabolic growth promoting hormone, which causes increased neonatal fat deposition and abdominal girth with increased birth weight.
Briefly describe the MIG Trial
Aim: To rule out a 33% increase in a composite of perinatal complications in infants of women treated with Metformin as opposed to Insulin
Randomised: to Metformin up to 2500mg / day (+Insulin if required to achieve glycaemic control), or Insulin
Primary outcome: Composite measure of neonatal outcome including neonatal hypoglycaemia, RDS, PTB, low APGARS etc
Results: No difference in the primary outcome between both groups
I.e Metformin safe in pregnancy
Less SEVERE neonatal hypoglycaemia in the Metformin Group
Of women in the Metformin group, 46% needed Insulin as well
Women referred metformin treatment to taking insulin
What was the only intervention that was found to PREVENT women from developing GDM
Cochrane 2020
Diet and exercise (combined)
What are the OGTT values used to diagnose GDM?
fasting >/= 5.1
1 hour >/= 10
2 hour >/= 8.5
What HbA1c levels indicate insulin resistance and diabetes mellitus?
IR = 42-47 DM = >/=48
Who requires GDM screening at earliest opportunity after pregnancy confirmed? And how is this screening conducted?
2 moderate OR 1 major risk factor:
High risk factors for GDM
• Previous GDM
• Previously elevated blood glucose level
• Maternal age ≥40 years
• Family history DM (1st degree relative with diabetes or a sister with GDM)
• BMI > 35 kg/m2
• Previous macrosomia (baby with birth weight > 4500 g or > 90th centile)
• Polycystic ovarian syndrome
• Medications: corticosteroids, antipsychotics
Moderate risk factors for GDM
• Ethnicity: Asian, Indian subcontinent, Aboriginal, Torres Strait Islander, Pacific Islander, Maori, Middle Eastern, non‐white African
• BMI 25 – 35 kg/m2
Screening:
HbA1c AND 75g 2h OGTT at earliest opportunity after pregnancy confirmed. Repeat OGTT at 24-28 weeks if not diagnostic in early pregnancy.
What is the risk of PET in GDM, T1DM, T2DM and DM with nephropathy?
GDM - 10%
T1DM, T2DM - 15-20%
DM with nephropathy - up to 50%
What should occur at the initial visit for women with pre-existing DM?
Booking bloods
HbA1c
Creatinine
ACR
retinopathy screening (if not within last 3 months)
Ensure taking higher dose 5mg folic acid and iodine
Check height, weight, BMI and BP
Screen for CVD risk factors
Review medications - change to metformin +/- insulin
Counselling around risks of adverse obstetric outcomes, and potential disease progression in pregnancy
Also: TFTs and consider coeliac serology screening in T1DM
When should delivery be planned for T1DM/T2DM and GDM?
T1DM/T2DM = 37-38+6 (risk stillbirth increases dramatically from 39wk) GDM = Delivery by 40+6; earlier dependant on risk factors
What are the risks and what is the counselling for a woman with diabetes and LGA baby >/= 4.5kg?
20% risk of shoulder dystocia.
Offer ElCS.
NB. NNT 443 to prevent 1 permanent brachial plexus injury.
What are the diagnostic levels for pre-existing DM?
fasting >/= 7.0
2 hour >/= 11.1
Random glucose >/= 11.1
What are the glycemic targets for women checking BSLs?
Fasting = 5.3
1 hour post meals = 7.4
2 hours post meals = 6.7
Pre- existing diabetes - aim to maintain HbA1C = 48 if possible without risk of hypoglycaemic episodes
How to initiate treatment in new diagnosis GDM
If fasting glucose < 7:
- Diet and lifestyle for up to 2 weeks
- If BSLs not controlled, commence metformin
- If metformin not successful or not tolerated, commence insulin
If fasting glucose >/= 7; macrosomia; diabetic complications (retinopathy/nephropathy)
- Commence insulin
When should BSLs be checked?
T1DM
- Fasting, pre-meal, 1 hour post-meal, evening
T2DM/GDM on bolus short-acting insulin
- Fasting, pre-meal, 1 hour post-meal, evening
T2DM/GDM on diet, metformin or single dose long acting insulin:
- Fasting, 1 hour post-meal
What is the perinatal mortality rate for women with pre-existing diabetes T1DM/T2DM?
28 per 1000 births
How does diabetes affect the risk of congenital abnormality?
The risk of congenital abnormality doubles.
(Background risk roughly 2.5%)
Commonest abnormality:
- Congenital heart malformation
- Neural tube defects (incl: micro-/anencephaly)
Risk highest if HbA1c >/= 86 - women should be advised to use contraception until diabetic control improved.
Dose dependent relationship between risk of abnormality and HbA1c levels prior to 10 week pregnancy.
What are the long term complications of GDM? What follow-up is required postpartum?
30% recurrence risk in future pregnancies
50% risk of developing T2DM in later life
Increased risk of high BMI and diabetes in the fetus
Recommend HbA1c at 12 wks
- If pre-diabetic repeat after further 12 weeks
- If >/=48 requires initiation of management for diabetes
Annual HbA1c screening
Describe the HAPO 2008 study.
Large blinded cohort study.
Aiming to find out if hyperglycaemia less than the threshold for diabetes mellitus had adverse pregnancy effects
Inclusion: OGTT by 32 weeks fasting <5.8, 2hr <11.1.
FINDINGS:
- Even below threshold for Dx overt DM, increasing serum glucose levels correlated with several adverse obstetric outcomes
- Increased risk of:
1st outcome = LGA >90th, neonatal hypoglycaemia, CS delivery, cord blood c-peptide
2nd outcome = PET, shoulder dystocia, birth injury, preterm birth, NICU admission, hyperbilirubinemia
What are the effects of pregnancy on pre-existing diabetes?
- Increasing insulin requirements
- Risk of deterioration of diabetic nephropathy (most likely if mod/severe renal impairment)
- Deterioration in diabetic retinopathy
- Increased risk of hypoglycaemia
- hypoglycemia unawareness
- DKA is rare, but can be exacerbated by hyperemesis, sepsis or prolonged labour
- Deterioration in autonomic neuropathy and gastric paresis
What are the additional obstetric risks for women with pre-existing diabetes?
Maternal:
- PET
- Shoulder dystocia
- CS delivery
Fetal:
- Miscarriage
- Stillbirth
- Perinatal/neonatal death increased 5-10 fold
- Congenital anomalies increased 2-3 fold (NTD, heart defects, sacral agenesis)
- Macrosomia
- Polyhydramnios
- Birth injury
- Neonatal hypoglycemia
- jaundice
- RDS
Why are babies of diabetic mothers prone to jaundice?
Hyperinsulinemia and increased fetal growth creates a state of relative hypoxia, driving extra medullary erythropoeisis and polycythemia.
What additional antenatal care is required in pre-exisitng diabetes?
- Pre-preganncy evaluations and counselling
- Management under tertiary centre, with MDT input
- Medication optimisation
- Close serum glucose onitroing with glucometer
- Ketone testing strips (if become hyperglycaemic or if unwell)
- 5mg folic acid through 1st trimester
- Early dating and viability scan
- Routine nuchal scan
- Detailed tertiary anatomy scan and cardiac echo
- Growth scans through third trimester
- PET assessment at each visit
- Planning around timing of delivery - IOL before 39 weeks
Intrapartum considerations for women with T1DM.
- Insulin-dextrose sliding scale
- Potassium replacement
- Hourly BSL - aim 4-7 g/L
- CTG
- CS only for obstetric indications
- After delivery of placenta reduce insulin rate by half
- Once E&D can restart SC insulin at pre-pregnancy dose, or 25-40% reduction
