Gestational Diabetes: Diagnosis and Treatment
Gestational diabetes, or diabetes during pregnancy, refers to elevated blood sugar levels that either develop for the first time during pregnancy or were present prior to conception. This condition can significantly affect both maternal health and fetal development. Therefore, regular screening, accurate diagnosis, and proper treatment are of great importance.
Types and Causes of Diabetes in Pregnancy
Diabetes in pregnancy is classified into two main categories:
- Pregestational diabetes: Diabetes diagnosed before pregnancy, seen in about 1% of all pregnancies.
- Gestational diabetes: Diabetes that develops or is first detected during pregnancy, occurring in 1 out of every 6–7 pregnancies.
Although the exact cause of gestational diabetes is not fully understood, it is known that hormones produced by the placenta in later pregnancy can lead to insulin resistance—a condition in which the body becomes less responsive to insulin. As a result, glucose is not effectively transported into cells, leading to elevated blood sugar levels in the mother.
This excess glucose passes through the placenta to the baby, causing increased insulin production in the fetus, which can result in fetal overgrowth (macrosomia). Babies with macrosomia face a higher risk of birth trauma, including shoulder dystocia (difficulty during delivery).
Risks Associated with Gestational Diabetes
Gestational diabetes poses several risks for both mother and baby.
For the mother:
- Preeclampsia (pregnancy-related hypertension)
- Sudden fetal loss
- Excessive weight gain
- Increased likelihood of cesarean delivery
For the baby:
- Macrosomia (large baby)
- Shoulder dystocia during birth
- Low blood sugar (neonatal hypoglycemia)
- Respiratory distress
- Higher risk of obesity and Type 2 diabetes later in life
For these reasons, timely screening and management are crucial.
How Is Gestational Diabetes Diagnosed?
Two main testing methods are commonly used for diagnosis:
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Two-step approach:
- A 50-gram oral glucose challenge test (GCT) is performed, regardless of fasting.
- Blood glucose is measured one hour later.
- A value below 140 mg/dL is considered normal.
- If the result is higher, a 100-gram oral glucose tolerance test (OGTT) is performed on another day.
- If two or more of the four measured values exceed the normal range, the diagnosis is confirmed.
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One-step approach (recommended alternative):
- A 75-gram OGTT is performed after fasting.
- Blood glucose is measured at fasting, 1 hour, and 2 hours.
- The diagnosis is confirmed if any single value exceeds:
- Fasting: ≥92 mg/dL
- 1 hour: ≥180 mg/dL
- 2 hours: ≥153 mg/dL
Early screening is recommended for women over 35, those who have previously given birth to a large baby, have a family history of diabetes, or had gestational diabetes in a prior pregnancy.
For women without risk factors, testing is typically performed between 24–28 weeks of gestation.
Safety of Screening Tests
Many expectant mothers wonder whether the glucose tolerance test is safe for the baby. Decades of worldwide research have shown no evidence of harm from these tests. On the contrary, diagnosing gestational diabetes early prevents serious complications for both mother and child.
Treatment of Gestational Diabetes
Once diagnosed, the first step in treatment includes:
- Regular blood glucose monitoring
- A personalized nutritional plan
- Moderate physical activity approved by the physician
The goal is to maintain:
- Fasting blood glucose below 95 mg/dL
- Two-hour post-meal blood glucose below 120 mg/dL
With these adjustments, 80–90% of pregnant women can achieve normal glucose control. If diet and exercise are insufficient, insulin therapy is initiated.
Insulin acts only within the mother’s bloodstream and does not cross the placenta, making it safe for use during pregnancy.
Monitoring After Delivery
Women diagnosed with gestational diabetes should continue monitoring fasting, postprandial, and nighttime glucose levels throughout pregnancy. About 6 weeks after delivery, a 75-gram OGTT should be repeated to determine whether diabetes has resolved or persisted.
It is important to note that gestational diabetes increases the long-term risk of developing Type 2 diabetes—with a 50% likelihood within 20 years after pregnancy.
Therefore, maintaining a balanced diet, regular exercise, and a healthy body weight postpartum is vital for long-term health.
Risk Factors for Gestational Diabetes
Certain factors increase the risk of developing diabetes during pregnancy, including:
- Advanced maternal age
- Overweight or obesity before pregnancy (BMI >30)
- Family history of diabetes
- History of delivering a large baby
- Polycystic ovary syndrome (PCOS)
- History of gestational diabetes in previous pregnancies
Women with these risk factors should undergo early glucose screening at the beginning of pregnancy to ensure timely diagnosis and management.
