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New Born OB
 

Gestational Diabetes Quick Facts     PB180

 

-          Early Screening – recommended in overweight and obese women with additional risk factors (can use either 50g or 75g…but if 75g, just do the fasting and 2-hour values)

o   Risk factors = physical inactivity, 1st degree relative with DM, high-risk race/ethnicity, prior infant >4000g, prior GDM, HTN (140/90 or tx), HDL <35, triglycerides >250, PCOS, prior A1c 5.7% or higher (or other test showing impaired glucose tolerance), BMI 40+, acanthosis nigricans, h/o cardiovascular disease

 

-          Routine Screening – all pregnant women between 24-28 weeks gestation (use the 50g for screening…cutoffs of 130, 135 and 140 are all acceptable)

o   If 50g is abnormal, then proceed with diagnostic 100g…traditionally required 2 elevated values for dx, but also acceptable to use 1 elevated value for dx

  • We use the Carpenter Coustan cut-offs of 95-180-155-140

-          Repeat Screening – women with an abnormal screening test but normal diagnostic test in the 1st trimester should have repeat testing at 24-28 weeks (okay to skip directly to 3h diagnostic test)

     Blood Glucose Monitoring – should be done 4x/day (at least until control is proven), should be reviewed weekly by physician (more or less frequently depending on control)

-          Fasting: goal <95

-          Post-prandial: can do 1-hour (goal <140) or 2-hour (goal <120), neither is superior

 

Risks of Gestational Diabetes

-          Maternal: hypertensive disorders, C/S, DM later in life (70% will develop GDM w/in 20-30y)

-          Fetal: macrosomia, hypoglycemia, hyperbilirubinemia, shoulder dystocia, birth trauma, stillbirth

 

Benefits of Treatment: reductions in preeclampsia/HTN disorders, LGA, C/S, shoulder dystocia

 

Treatment Modalities

1.       Diet – the ADA recommends registered dietician counseling and development of a personalized nutrition plan based on BMI for all pts with GDM…three major components

a.       Caloric allotment

b.      Carbohydrate intake – 40% carbs, 40% fat, 20% protein

c.       Caloric distribution – 3 meals and 2-3 snacks

2.       Exercise – 30 minutes of moderate intensity aerobic exercise at least 5 days/week, walking 10-15 minutes after each meal

3.       Insulin – standard therapy for GDM refractory to diet/exercise as per ADA, typically started at 0.7-1.0 units/kg/day

a.       NPH is the preferred long-acting agent. Onset 1-3h, peak 5-7h, duration 13-18h.

b.      Lispro/Aspart are preferred short-acting agents. Onset 1-15m, peak 1-2h, duration 4-5h.

4.       Oral Diabetes Medications – not FDA approved for GDM and considered 2nd line by ADA

a.       Metformin – a biguanide, inhibits hepatic gluconeogenesis and glucose absorption, also stimulates glucose uptake in the periphery

                                     i.      Advantages: equivalent glycemic control and outcomes compared to insulin

                                     ii.      Disadvantages: crosses the placenta with unknown long-term consequences, may increase risk of preterm labor

b.      Glyburide – a sulfonylurea, binds to pancreatic cells to increase insulin secretion, also increases insulin sensitivity in the periphery

                                     i.      Advantages: none

                                     ii.      Disadvantages: worse neonatal outcomes (despite equivalent glycemic control compared to insulin), crosses the placenta with unknown long-term effects

 

Fetal Surveillance – typically started at 32 weeks is women with poorly-controlled GDM or GDM requiring medication, specific test and frequency of testing is unknown although testing that incorporates amniotic fluid measurements in probably better given that GDM is associated with polyhydramnios (there is no consensus re: surveillance in women with well-controlled A1GDM)

 

Ultrasound – “reasonable for clinicians to assess fetal growth by ultrasonography” in an attempt to identify macrosomia, although only ~22% of fetuses identified as macrosomic on US will actually be LGA at birth AND most cases of macrosomia aren’t severe enough to alter delivery planning

 

Delivery Timing – elective C/S counseling only if EFW is >4500 grams

-          Well-controlled A1GDM: delivery between 39 0/7 – 40 6/7

-          Well-controlled A2GDM: delivery between 39 0/7 – 39 6/7

-          Poorly-controlled GDM: delivery between 37 0/7 – 38 6/7 (earlier only if inpatient attempts to improve glycemic control have failed or if antepartum testing is abnormal)

 

Postpartum Management – screen for diabetes at 4-12 weeks post-partum with a 75g 2-hour OGTT

-          Normal = fasting <100 and 2h <140

o   Lifestyle counseling, retest every 1-3 years

-          Impaired = fasting 100-125 or 2h 140-199

o   Lifestyle counseling, consider referral for management, consider Metformin if both values abnormal, retest every 1 year

-          Diabetes = fasting >125 or 2h >200

o   Refer for management