Overview
Gestational diabetes is high blood sugar that develops or is first identified during pregnancy. It affects 7-10% of pregnancies. It is usually screened between weeks 24-28.
It usually resolves after delivery; however, it poses risks of type 2 diabetes for the mother and various problems for the baby.
Symptoms
It usually does not cause symptoms; that is why routine screening is important. Sometimes:
- Excessive thirst
- Frequent urination (difficult to distinguish from pregnancy)
- Fatigue
- Blurred vision
- Unexplained weight loss
- Recurring infections
Causes
Placental hormones (human placental lactogen, estrogen, cortisol) create insulin resistance. In some women, the pancreas cannot produce enough additional insulin, leading to gestational diabetes.
Risk Factors
- Pregnancy over age 25
- Excess weight, obesity
- Family history of type 2 diabetes
- Previous gestational diabetes
- Previous baby over 4 kg
- Previous unexplained stillbirth
- Polycystic ovary syndrome
- Ethnicity (Mediterranean, Asian, African)
- High blood pressure
- History of unexplained miscarriage
Complications
In the baby:
- Macrosomia (large baby, >4 kg)
- Birth trauma (shoulder dystocia)
- Preterm birth
- Hypoglycemia after birth
- Respiratory distress syndrome
- Jaundice
- Congenital anomalies (in poor control)
- Childhood obesity risk
- Adult type 2 diabetes risk
- Stillbirth (rarely)
In the mother:
- Preeclampsia
- Increased cesarean risk
- Polyhydramnios (excess amniotic fluid)
- Postpartum type 2 diabetes (50% risk in 10 years)
- Recurrence in subsequent pregnancies
Screening and Diagnosis
Screening (weeks 24-28):
- 50 g glucose screening test: Blood sugar ≥140 mg/dL 1 hour later = positive
Diagnostic test (if positive):
- 3-hour 100 g OGTT or 2-hour 75 g OGTT
- Fasting: ≥95 mg/dL
- 1 hour: ≥180 mg/dL
- 2 hours: ≥155 mg/dL
- 3 hours: ≥140 mg/dL
- 2 or more elevated values = gestational diabetes
In high-risk patients:
- HbA1c, fasting glucose at first prenatal visit
Treatment
1. Nutrition (foundation treatment):
- Dietitian support is essential
- Regular meals (3 main + 2-3 snacks)
- Carbohydrate counting
- Low glycemic index carbohydrates (whole grains, legumes)
- Adequate protein
- Healthy fats
- Plenty of vegetables
- Avoid sugary and processed foods
- Limited fruit, with meals
2. Exercise:
- Regular moderate-intensity exercise with doctor's approval
- Walking, swimming, prenatal yoga
- 30 minutes per day
- Walking after meals is very effective
3. Blood sugar monitoring:
- 4 times a day (fasting + 3 postprandial)
- Targets:
- Fasting: <95 mg/dL
- 1-hour postprandial: <140 mg/dL
- 2-hour postprandial: <120 mg/dL
4. Medication:
If diet and exercise are insufficient:
- Insulin: Gold standard, does not cross placenta
- Metformin: In some situations (oral)
- Glyburide: In some situations (oral)
Delivery and Postpartum
Delivery:
- Usually at weeks 39-40
- Cesarean rate increases
- Early delivery may be considered if macrosomia present
- Newborn blood sugar closely monitored
Postpartum:
- Blood sugar usually returns to normal
- 75 g OGTT repeated at 6-12 weeks
- Then diabetes screening every 1-3 years (lifelong)
- Breastfeeding recommended (protective for mother and baby)
Prevention
Before pregnancy:
- Healthy weight (pre-pregnancy)
- Regular exercise
- Healthy nutrition
- HbA1c control (previous risky pregnancy)
During pregnancy:
- Recommended weight gain (underweight: 12-18 kg, normal: 11-16 kg, overweight: 7-11 kg, obese: 5-9 kg)
- Regular exercise
- Healthy nutrition
- Regular prenatal check-ups
- Do not skip screening tests
Postpartum (preventing type 2 diabetes):
- Healthy weight gain
- Regular exercise
- Healthy nutrition
- Breastfeeding
- Regular diabetes screening (lifelong)
- Monitor symptoms indicating type 2 diabetes risk