12. Pregnancy and diabetes mellitus. Gestational diabetes Flashcards
definition of gestational diabetes mellitus (GDM)
glucose intolerance with onset or first recognition after 20 weeks gestation.
occurs in 6-12% of pregnancies in the US.
what is pregestational diabetes mellitus?
diabetes present before pregnancy and may be either type 1 or type 2 diabetes.
Diagnostic criteria of pregestational diabetes
any one of the following:
1) HbA1C > 6.5%
2) fasting plasma glucose > 7.0 mmol/L
3) OGTT 2 h’ plasma glucose > 11.1 mmol/L
4) random plasma glucose > 11.1 mmol/L with typical symptoms.
risk factors for Gestational diabetes
- Personal history of IGT, IFG or HbA1C ≥ 5.7
- Previous unexplained perinatal loss or birth of a malformed infant
- GDM in a previous pregnancy
- Family history of diabetes (1st-degree relative)
- Glycosuria at the first prenatal visit
- High-risk race/ethnicity
- Previous birth of an infant ≥ 4000 g
- Pre-pregnancy weight ≥ 110% of ideal body weight or BMI > 30 kg/m2
- Dyslipidemia
- Medical condition associated with development of diabetes (metabolic syndrome, PCOS, corticosteroid use, HTN, CV disease)
- Excessive gestational weight gain during the first 18-24 weeks
- Maternal age (> 30 years of age)
- Multiple gestation
what teratogenic effect does Fetal hyperglycemia have?
- congenital defects
- vascular effect (predisposes to fetoplacental
insufficiency, IUGR risk)-1st trimester - macrosomia (predispose to birth trauma,
shoulder dystocia, Erb palsy)-3rd trimester
pathophysiology of GDM
combinations of hormonal changes of pregnancy (hPL, progesterone, prolactin, cortisol), metabolic changes in pregnancy and risk factors leading to insulin resistance–> maternal hyperglycemia–> fetal hyperglycemia (teratogenic effect)
when is screening for GDM performed?
at 24-28 weeks gestation
earlier screening is recommended only for high-risk patients
what is the Two-step screening approach?
The most widely used approach for identifying pregnant women with GDM in the US.
The first step is a 50-gram 1-hour glucose challenge test (GCT) without regard to time of day/previous meals.
Screen-positive patients (> 7.8 mmol/L) go on to the second step- a 100-gram 3-hour oral glucose tolerance test (OGTT), which is the diagnostic test for GDM.
what is the One-step approach?
This approach omits the screening test and simplifies diagnostic testing by performing only a 75-gram 2-hour OGTT but requires an overnight fast.
Fasting plasma glucose > 5.6 mmol/L
2 h’ plasma glucose > 7.8 mmol/L
Positive screening → GDM diagnosed
what should not be used for GDM screening?
Fasting glucose, random plasma glucose, HbA1C
what is the recommended daily carbohydrate intake to maintain good glycemic control?
175 gram
Antepartum management of GDM
- Patient education
- Diet and exercise
- If pregestational diabetes, check treatment regimen: change orals to injectable insulin, exclude any teratogenic agents
- Oral anti-diabetic which can be used during pregnancy include metformin and glyburide (2nd gen’ sulfonylurea)
*Oral antidiabetics are NOT used in the EU - All women should be on pre-conceptional folate
what are the glycemic targets in antepartum and postpartum management?
- HbA1C < 7%
- Fasting BG < 95 mg/dL (5.3 mmol/L)
- 1-hour postprandial BG < 140 mg/dL (7.8 mmol/L)
- 2-hour postprandial BG < 120 mg/dL (6.7 mmol/L)
what are the glycemic targets during pregnancy management?
- Postprandial BG < 140 mg/dL (7.8 mmol/L)
what is the management of GDM during pregnancy?
- Adequate surveillance (both maternal and fetal)
- Obstetric US, fetal Echo, maternal AFP → obtain at 16-20 weeks to monitor for congenital anomalies
- US examination at 36-39 weeks gestation to evaluate
fetal size - NST should start at 32 w’;
from 36 w’ onwards → perform twice weekly - Diet and exercise
- Achieve glycemic control with injectable insulin
(basal-bolus approach)
*Consider ↑↑ insulin demand during pregnancy
