Diabetes in Pregnancy Flashcards
Different categories of diabetic patients you may encounter in antenatal clinic
- Pre-existing
- T1DM
- T2DM
- MODY, LADA
- Pre-diabetes/impaired glucose tolerance
- Gestational diabetes
Pre-diabetes/impaired glucose tolerance - HbA1c criteria for this category at booking/non-pregnant
HbA1c 41-49
(In NZ HbA1c cut off = 50 is diagnostic for diabetes in a non-pregnant patient)
Appropriate for direct referral to ADHB diabetes in pregnancy clinic
Definition of Type 1 Diabetes (1A and 1B)
Insulin deficiency
- Due to destruction of pancreatic ß-cells
Type 1a
- Autoimmune destruction
- Positive for antibodies to islet cells, GAD (Glutamic acid decarboxylase), insulin & tyrosine phosphatases
Type 1b: idiopathic therefore no antibodies
Type 2 diabetes - definition
Insulin resistance/deficiency through environmental (diet, lifestyle) or genetic factors (FHx, ethnicity)
Definition of LADA
Latent Autoimmune Diabetes in Adults
Predominantly in Scandinavian populations with variable titres of autoantibodies
Definition of MODY, mode of inheritance, number of subtypes
Mature Onset Diabetes of the Young
- Non-insulin dependent diabetes
- Diagnosed <25yo
- Autosomal dominant inheritance
- No antibodies
- Diagnosed by genetic testing. Subtypes defined by specific genetic defects – MODY 1-6
Gestational diabetes definition, incidence in pregnancy
Impaired glucose tolerance of variable severity, which either develops during, or is first recognised, in pregnancy
15% incidence in pregnancy
50g polycose test: what kind of test is this? Rate of false negative?
Screening test, 25% false negative rate, therefore should only be offered to low risk women
However should still discuss polycose vs OGTT with low risk women - they may prefer to have the diagnostic test instead
Polycose: criteria for a positive screening test
I hr glucose >11.0mmol/L, refer straight to
diabetes clinic
1 hr glucose 7.8-11.0mmol/L, 75 g
OGTT within a week
Timing of OGTT in pregnancy, and diagnostic criteria
24-28 weeks (24 in women with RFs)
75g glucose challenge
Fasting ≥ 5.5 mmol/l, or
2 hour glucose ≥ 9.0 mmol/L in NZ (8.5 in Aus)
GDM risk factors
Pre-existing
- Prev GDM, macrosomia, PET, unexplained perinatal loss/pre-term birth
- PCOS
- Obesity
- Age
- Ethnicity (Asian, Hispanic, Pacific)
- Chronic hypertension
- Steroid or antipsychotic medications
- Family history of diabetes
This preg:
- Booking HbA1c borderline
- Multiple pregnancy
- Macrosomia
Pre-existing diabetes: pre-pregnancy. Assess diabetes control: history/exam/investigations
Discuss contraception. Planning pregnancy? When? Discuss assessing and optimising diabetes control and lifestyle factors prior to pregnancy to reduce pregnancy risks
Type of diabetes, duration
Glycaemic control
Type of medication (metformin, insulin, sulfonylureas) - are these ok for pregnancy
Known diabetic complications (nephropathy, retinopathy, HTN)
Other RFs: age, other medical
conditions, past obstetric history
Weight, BP
Investigations:
- HbA1c
- U+E, creatinine, LFTs, FBC ferritin, TFTs, lipids
- If renal impairment: K+, Ca2+, phosphate, albumin and urea
- B12 if vegetarian
- Vitamin D if RFs for deficiency (coeliac, very pale skin,
no sun exposure, and women with darker skin (include all Indian women, as very high rates
of vitamin D deficiency)
- MSU, urine dip - ACR if proteinuria
- Booking bloods
- Check smears UTD
- Chase last eye screening
- ECG if high risk of cardiovascular complications: > 10 years (discuss), age > 40/45, younger age if
other risk factors such as smoking, plus obesity
T1 DM - additional pre-pregnancy investigations?
Thyroid antibodies for type 1: every 2 years if negative. If positive, no need to repeat
Coeliac screen for type 1: every 2 - 5 years if negative. If positive, may require referral for
endoscopy and biopsy to confirm diagnosis
Pre-existing diabetes, pre-preg or early pregnancy: medication counselling
Metformin - ok to continue Insulin - continue Sulfonylureas - stop, change to insulin Statins - stop Antihypertensives - ideally switch pre-preg to a pregnancy-friendly agent. If found out pregnant and was on ACE-inhibitor first trimester, still ok but switch to another agent ASAP
Pre-preg: high dose folic acid 5g at least 6 weeks pre-conception, and throughout the pregnancy
Iodine 150mcg throughout pregnancy
Consider low dose aspirin from 12 weeks (ideally start week 12-16, but up to 20 ok) and Ca supplementation
Pre-existing diabetes: trend in insulin requirements in first and second trimester? (from ADHB guideline)
Typically in first trimester, insulin requirements might increase, especially overnight in very early pregnancy
However between 9 - 13 weeks requirements usually decrease significantly, as women are more
insulin sensitive and hypoglycaemia can be a problem
16 - 20 weeks, women usually become more insulin resistant. Encourage women to increase their insulin doses adequately, especially mealtime boluses,
which typically increase more than the basal insulin (often end up with 2/3 insulin as bolus, 1/3
basal).
Many women fall behind with their treatment between 20 - 28 weeks’ gestation
Pre-existing diabetes: Hypoglycaemic unawareness may occur with tighter control. What advice to give to women about hypoglycaemia?
- BSL 5 before they drive
- Not to drive within 45 minutes of treating hypoglycaemia
- Ensure glucagon has not expired
- Recommend MedicAlert bracelet
Diabetes in pregnancy - timing of growth scans in third trimester?
28 and 36 weeks gestation, plus others as indicated
for obstetric concerns
Diabetes in pregnancy: general advice and goals for pregnancy
- Achieve normoglycaemia
- Prevent ketosis (DKA can occur more rapidly with high mortality and intellectual effect on offspring)
- Discuss adequate weight gain
- Dietician input
Timing of repeat HbA1c in pregnancy
HbA1c at 28 and 36 weeks with routine bloods
May do at 16 - 20 weeks as well in pre-existing diabetes
BSL testing timing and targets: GDM, T2DM, T1DM
GDM and T2: QID
- Fasting aim
Diabetes caloric requirements - ratio of carbs/fat/protein etc
Dietary composition is usually recommended as
18 - 20% protein
< 10% saturated fat, < 10% polyunsaturated fat
60 - 70% monounsaturated fat and carbohydrate
Indications to avoid or cease metformin?
- Significant fetal growth restriction reflecting a probable placental problem (all right to use if constitutionally small fetus)
- Ongoing maternal weight loss
- Maternal contra-indications such as sepsis, significant GI upset,
preeclampsia, renal failure or conditions that put women at risk of lactic acidosis
Maternal risks of diabetes in pregnancy
REMEMBER: different risk profiles for leaner and obese women, and for poor/good control
- Increased risk of miscarriage with increasing peri-conceptual hyperglycaemia
- Hypertensive disorders/preeclampsia
Risk PET with GDM are 3 - 5%
Risk PET with T1: up to 15 - 20% Good diabetes control reduces the risk of preeclampsia. - Operative delivery
- Birth trauma
Fetal risks of diabetes in pregnancy
REMEMBER: different risk profiles for leaner and obese women, and for poor/good control
- Polyhydramnios
- Macrosomia (particularly high post-prandial BSLs)
- Congenital abnormalities
(10% risk of abnormalities if HbA1c >100 at conception, if high risk get a tertiary anatomy scan) - IUGR with a raised HbA1c due to small placenta
- Preterm birth
- Birth trauma (shoulder dystocia)
- Perinatal mortality (particularly associated with abnormal fasting BSLs)
- Neonatal respiratory and metabolic complications (particularly associated with abnormal fasting BSLs)
- Increased risk to infant of obesity, diabetes, inattention/hyperactivity and impaired motor skills
Pregnancy risks specifically for T1DM
Caesarean section
- 45% vs 12% background risk (4-fold increase)
LGA
- 30% vs 4% background risk (6-fold increase)
Shoulder dystocia
- 15% vs <0.2% background risk (15-fold increase)
Pre-eclampsia
- 15% vs 2% background risk (7-fold increase)
Preterm birth
- 20% vs 5% background risk (4-fold increase)
Perinatal mortality
- 20:1000 vs 5:1000 background risk (4-fold increase)
Increased risk of thyroid disease in pregnancy & increased risk of infection
Worsening of existing retinopathy & nephropathy
Intrapartum management: timing of delivery
38 weeks if macrosomia (or earlier if significant concerns re: diabetic control, maternal/fetal concerns)
After 38 weeks if normal growth, to reduce risk of shoulder dystocia, LGA, CS, SB
(NICE, 2008)
Evidence - IOL for GDM with no macrosomia
Cochrane 2018 - included 1 x RCT (GINEXMAL) that compared IOL vs
expectant management in women with GDM and no macrosomia
No difference in CS, assisted vaginal birth, shoulder dystocia, PPH, low agars, NICU admissions.
Limitations:
- Study did not reach sample size
- Underpowered to detect differences in uncommon outcomes
- Excluded EFW >4000g
- More nullipara in IOL group
Findings may not be generalisable to NZ population: mean BMI
25, 75% white, >50% diet controlled only, different methods of diagnosing GDM
Intrapartum BSL monitoring frequency
Hourly in labour
- aiming for 4-7mmol/L
intravenous dextrose and insulin for type 1s from onset of established labour, or those not maintained 4-7
Q30min if GA
(NICE)
Postpartum neonatal BSL testing frequency (NICE)
2-4 hours after birth with feeding as soon as possible after birth then every 2-3 hours
ADHB needs 3 normal BSLs prior to discharge
Postpartum BSL management for T1DM + T2DM
T1 DM: halved insulin dose
T2DM: monitoring of BSLs then re-commencement of medication based on BSL trends
Return to routine diabetes care
Discuss importance of contraception and pre-conception planning
Postpartum BSL management for GDM
Continued BSL monitoring 24h to ensure normoglycaemic
Advice on lifestyle changes to prevent development of type 2 diabetes
Contraception discussion
HbA1c at 3 months
GDM long term prognosis for recurrence of DM, T2DM
30% risk of recurrence GDM
Up to 50% risk of developing T2DM within 10-20 years
Individualised monitoring after pregnancy for cardiovascular risk factors and perceived DM risk
Hyperemesis T1DM: do they require insulin even if they are unable to eat?
YES
Very important as women with type 1 diabetes will require insulin even if they are not able to eat. They usually require a glucose insulin infusion
Note at ADHB: . the antenatal infusion protocol does not routinely have potassium added. Clinicians should prescribe appropriate potassium replacement in other IV fluids or specifically request addition of potassium to the
glucose/insulin infusion
T1DM NBM/severe hyperemesis: on glucose insulin infusion
a) frequency of BSL testing
b) what if she is eating but vomiting intermittently?
c) what if she starts to eat again and is keeping everything down?
c)
a) q1-2h
b) give short acting insulin boluses AFTER eating (30 min from start of eating) - doses based on food eaten and whether woman feels nauseated. TEMPORARY MEASURE ONLY
c) Change back to subcut insulin, doses should be decided by physician. If eating is sporadic, some women keep infusion going with small SC bolus of insulin using her insulin pen when she eats
(ADHB)
Hyperemesis T2DM/GDM - what medication to withold?
Metformin
HAPO trial results (brief)
Showed that risk of adverse outcomes is on a continuum with
maternal glucose levels with no threshold
Strong association with maternal glucose levels and BW, C
peptide levels, PET, SD, birth injury, premature delivery, NICU,
jaundice.
Reduces perinatal outcomes RR 0.32
Weak association with maternal glucose levels and Macrosomia +
Neonatal Hypoglycaemia
ACHOIS trial results (brief)
Showed that treating GDM (OGTT 2hr level 7.8-11.1) improved
outcomes compared to standard care
Improvement in composite perinatal outcome (death, SD,
fracture, nerve palsy), reduced birthweight, reduced LGA
Showed no difference in CS rates
Increased NICU admissions maybe related to increased awareness
MIG results (brief)
Metformin (alone or with supplemental insulin) is not associated
an increase in perinatal complications compared to insulin
Women prefer metformin to insulin treatment
At 9 year follow up - infants of mothers treated with metformin
were larger by measurements but same metabolic outcomes and
total body fat percentage
Criteria for offering CS in GDM?
GDM and macrosomia 4.5kg
T2DM/GDM and NBM? Is a glucose/insulin infusion required? Monitoring of BSLs while NBM?
Not routinely
Monitor glucose hourly initially and inform physician if levels persistently above 7.0 mmol/L. If stable and within range, change to 2-hourly
Basic rules for starting insulin? GDM
Weigh the woman
Total insulin = 0.5 x weight
Total insulin = 1/3 basal + 2/3 bolus
Split the bolus into thirds, for each meal
If T1DM and NBM, how soon after steroids should the G/I infusion be modified?
If T2DM/GDM and NBM, does anything need to be done after steroids?
a) 8h, modify GIK, discuss with physicians
b) 8h post steroid may need G/I infusion, discuss with physicians
How much extra insulin do women require after steroids? When does this increase need to start? How long after does the steroid effect wane?
Usually twice their usual dose of insulin 8h after first steroid
Until 24 - 36 hours after the second steroid is given. Steroid effects often wane gradually after that, but occasionally women go back to their pre-steroid doses of insulin
quite abruptly.
Frequency of BSL monitoring with concurrent steroid administration
o Pre-meal
o 2 hours post-meal
o Pre-bed
o Overnight depending on control: at least a 02:00 hours test; or if having problems with
control, more frequently, especially if woman has type 1 diabetes with poor hypoglycaemic awareness. Testing may be 2 hourly, especially when establishing the
insulin dose required.
o Also check 1 and 2 hours after any correction dose is given.
o Check after treating any hypoglycaemia, 10 - 15 minutes and 1 hour later.
Hyperglycaemia - e.g. after steroids
What is a correction dose? How do we calculate it?
A correction dose is the amount of insulin a person needs to bring their blood glucose down 1 mmol.
This is calculated by adding up the total daily dose of insulin (short plus long-acting) and dividing by 100, e.g. if on 50 units/day, then 0.5 units decreases glucose by 1 mmol, if on 100 units/day, then 1 unit decreases it by 1 mmol.
Therefore, if a woman is taking 100 units/day usually, the initial increase during steroid administration should result in a daily dose of 200 units. If this dose is correct, then 2 units will bring the blood glucose down 1 mmol. So, if the capillary glucose level is elevated after the first insulin dose increase then give a correction to test whether doubling the dose is likely to work for the next injection.
Prior to the next meal, if the glucose level is above 4 mmol, then add a correction dose to bring
the glucose down to 4 plus double the meal insulin
