Gestational Diabetes

Snapshot

• A 38-year-old G3P2 woman at 28 weeks gestation presents to the clinic for a routine prenatal visit. At her last appointment, her OB/GYN noted that her fetus is large for her gestational age. Her fundal height at the current appointment is 33 cm (see chart in image). She has no chronic medical conditions and has never previously been diagnosed with diabetes. Her 1-hour postprandial glucose level is 212 mg/dL, 2-hour postprandial glucose level is 187 mg/dL, and 3-hour postprandial glucose level is 147 mg/dL. 

Introduction

• Overview
  • gestational diabetes mellitus is a condition characterized by glucose intolerance that is first recognized during pregnancy
• Epidemiology
  • prevalence
    • occurs in approximately 6% of pregnant women in the US
  • risk factors
    • obesity
    • family history of diabetes mellitus
    • maternal age > 30
    • having previously given birth to an infant weighing > 9 pounds
    • polycystic ovary syndrome
    • non-white race
• Pathophysiology
• ↑ hormones of pregnancy (i.e., estrogen, cortisol, and human placental lactogen) may ↑ risk of insulin resistance 

Presentation

• Symptoms
  • asymptomatic in majority of cases
  • increased thirst and ↑ frequency of urination
• Physical exam
• fetus size large for gestational age

Studies

• Oral glucose tolerance test
  • conduct a 1-hour 50 g oral glucose tolerance test
    • measure venous plasma glucose after 1 hour
    • perform at 24-28 weeks of gestation
    • ≥ 140 mg/dL is considered abnormal
  • conduct an oral 3-hour 100 g glucose tolerance test
    • confirm abnormal test if any 2 of the following are present
      • fasting glucose level > 95 mg/dL
      • glucose level after 1 hour > 180 mg/dL
      • glucose level after 2 hours > 155 mg/dL
• glucose level after 3 hours > 140 mg/dL

Treatment

• Lifestyle
  • strict adherence to a diabetic diet (eating healthy foods in moderate amounts and adhering to regular mealtimes)
    • indications
      • initial treatment
  • aerobic exercise and resistance training
    • indications
      • initial treatment
  • routine monitoring of fasting blood glucose and postprandial glucose levels
    • indications
      • initial treatment
• Medical
  • insulin
    • indications
      • elevated blood glucose level despite lifestyle modifications
  • metformin
    • indications
      • elevated blood glucose level despite lifestyle modifications
  • glyburide
    • indications
• elevated blood glucose level despite lifestyle modifications

Complications

• Maternal complications
  • ↑ risk of developing type II diabetes mellitus 
  • ↑ risk of developing cardiovascular disease
• Fetal complications
  • perinatal mortality
    • incidence
      • 2-5% of babies born to mothers with gestational DM
  • neonatal hypoglycemia  
    • ↑ amount of fetal insulin in the setting of a ↑ maternal glucose supply in utero
      • ß-cell hyperplasia in the newborn  
  • congenital defects
    • cardiac deformities 
      • secondary to trophic effect of insulin
    • macrosomia (> 4500 g)   
      • shoulder dystocia during vaginal delivery