Obstetrics & Gynecology
Gestational Diabetes Mellitus
임신성당뇨
Glucose intolerance first recognized in pregnancy (usually late 2nd–3rd trimester)
- How common
- 7–10% of pregnancies (Korea 6–10%)
- Typical age
- Higher risk >25, BMI ≥25, family history
What is it?
Placental hormones (hPL, cortisol, progesterone) cause insulin resistance → β-cell compensation fails → hyperglycemia.
Commonly affected: Maternal metabolism, placenta, fetal growth
How it develops
- Placental hormone secretionhPL, cortisol, progesterone rise
- Insulin resistanceReduced peripheral glucose uptake
- β-cell compensation failureInsulin secretion fails to compensate
- Hyperglycemia & fetal effectsFetal hyperinsulinemia, macrosomia, complications
Symptoms
- Macrosomia>4 kg, risk of shoulder dystocia
- PolyhydramniosFetal polyuria from hyperglycemia
- Recurrent candidiasisGlucosuria-driven infections
- Mostly asymptomaticDetected by screening
How it is examined
- 50 g glucose challengeAt 24–28 wk; 1-h ≥140 mg/dL → diagnostic test
- 100 g 3-h OGTTCarpenter-Coustan: ≥2 of fasting≥95, 1h≥180, 2h≥155, 3h≥140
- Growth ultrasound32–36 wk for macrosomia/AFI
Imaging
X-ray not used.
- Not applicable
Obstetric US: fetal AC, AFI, estimated fetal weight.
- Macrosomia
- Polyhydramnios
- AC >90th percentile
Non-surgical care
- Medical nutrition therapy40–50% complex CHO, scheduled meals, carb distribution
- Self-monitoring blood glucoseTargets: fasting <95, 1-h pp <140, 2-h pp <120
- Exercise30 min walking after meals
- Insulin (first-line drug)If MNT/exercise fails; basal-bolus regimen
- Metformin/glyburide (alternative)Alternative when insulin declined
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
Cesarean for estimated fetal weight ≥4500g or obstetric indication
Procedures that may be discussed
- Delivery at 39 wk if well-controlled
- Cesarean for macrosomia/shoulder dystocia risk
- Monitor neonatal hypoglycemia
Outlook
Resolves after delivery in most; 50% lifetime risk of T2DM. Repeat OGTT 6 weeks postpartum.