LM 15.7: Gestational Diabetes Flashcards
which ethnicities are at higher risk for GDM?
- native america
- AA
- Asian
- Hispanic
what is pre-gestational diabetes?
diabetes that exists prior to pregnancy
can be type I or type II
what is gestational DM?
diabetes diagnosed in pregnancy due to glucose intolerance which will typically resolve after pregnancy
correlates to an increased risk of type II DM later in life
what are the 2 classifications for GDM?
GDMA1 = diet controlled gestational diabetes
GDMA2 = medication controlled gestational diabetes
what are the risk factors associated with GDM?
- elevated BMI (30+)
- clinical conditions associated with insulin resistance
- PCOS
- h/o giving birth to infants over 4000 g
- first degree relative with DM
- history of GDM
- HTN
- CVD
- HbA1c over 5.7, impaired glucose tolerance or impaired fasting glucose on previous testing
why is pregnancy a diabetogenic state?
- fasting insulin levels increase due to increased demand and there is a concurrent progressively increasing post prandial glucose levels with simultaneous suppression of hepatic insulin sensitivity
this leads to an overall increased level of maternal circulating glucose
- later in prengnancy there is decreased peripheral insulin sensitivity due to placental trophoblasts secreting increased levels of human placental lactose (hPL) into maternal circulation to enhance nutrition for growing fetus
- at the same time, estrogen and progesterone stimulate B-cell hypertrophy also leading to increased insulin release – the placenta up regulates expression of GLUT1 transporters in the syncytiotrophoblasts allowing glucose to enter fetal circulation by facilitated transfusion
when do you screen for GDM?
at the initial OB visit when there are risk factors
otherwise, screen between 24-28 weeks gestation if there are no risk factors
how do you screen for GDM?
2-step method:
1. initial screening test using 50 gm glucose then testing glucose levels after 1 hr and if it’s over 130 or 140 depending on that areas criteria, then it would be positive test – do not need to be fasting
- follow up diagnostic test is a 3 hr 100 gm glucose challenge test where blood draws are obtained fasting prior to ingesting 100 gm glucose and then at 1, 2 and 3 hrs after ingestion
if 2 out of the 4 values are elevated then GDM diagnosis is made
does GDM have risk of congenital malformations?
in contrast to women with pregestational diabetes, women with GDM typically are not at increased risk of infants with congenital malformations because the onset of the disorder is after organogenesis, and do not experience diabetes-related vasculopathy because of the short duration of the disorder
what are the fetal effects of GDM?
- congenital anomalies
- preterm birth
- fetal growth restriction
- spontaneous abortion/stillbirth
- macrosomia
- neonatal hypoglycemia
- polyhydramnios
what are the most common fetal anomalies associated with pregestational DM?
- neurologic
anencephaly, holoprosencephaly, microcephaly
- skeletal
sacral genesis, caudal agenesis
- CV
VSD, transposition of great vessels, PDA, pulmonary stenosis
- renal
duplication of the ureter, renal agenesis
- urologic
hypospadias
which type of pregestational DM has a higher risk for fetal growth restriction?
type 1 DM
with preexisting microvascular complications or HTN, there is a 6-10x risk of fetal growth restriction than with woman without preexistent vascular disease
what is macrosomia/LGA?
macrosomia is a birth weight 4500+ gm while LGA is a fetal or neonatal weight that’s 90%+ for gestational age
LGA and macrosomia are the most common adverse neonatal outcomes associated with GDM and effects 40-60% of women with pregestational DM
it develops due to increased levels of insulin produced by the fetus in response to increased glucose levels that cross the placenta – this converts higher levels of glucose to fat resulting in heavier babies
what are the complications associated with macrosomia?
- increased risk of should dystocia and complications such as brachial plexus injury and/or fractions
- increased risk of operative deliver
what is neonatal hypoglycemia?
hypoglycemia in infants resulting from the hyperinsulinemia due to gestational DM
this can lead to adverse neurodevelopment outcomes
since glucose passes freely through the placenta from maternal circulation, the increased glucose due to maternal DM causes the fetus to increase insulin production
after birth, the fetus is no longer exposed to maternal hyperglycemia and elevated neonatal insulin levels may result in hypoglycemia
you have to diagnose this early because it can lead to potential fetal brain injury as the brain relies heavily on glucose to function
