What is Gestational Diabetes? Signs and Symptoms, Diagnosis, Treatment

What is Gestational Diabetes:

Gestational Diabetes
Patient UKGestational diabetes

Gestational diabetes is a form of diabetes that can develops during pregnancy (gestation) in a patient without prior history of diabetes. Gestational diabetes is similar to other types of diabetes and causes high blood sugar (glucose) levels, which can effect the pregnancy and baby’s health.
In gestational diabetes, blood glucose usually returns to normal soon after delivery. But having gestational diabetes puts the patient at high risk of developing type 2 diabetes. Patients with gestational diabetes must continue working with their health provided to monitor and manage their blood sugar.

This video tutorial on Gestational Diabetes has been provided by: Nucleus Medical Media

Risk Factors for Gestational Diabetes:

Pregnancy hormones can block insulin from doing its job. When this happens, glucose levels may increase in a pregnant woman’s blood.

You are at greater risk for gestational diabetes if you:

  • Are older than 25 when you are pregnant
  • Come from a higher risk ethnic group, such as Hispanic American, African American, Native
  • American, Southeast Asian, or Pacific Islander
  • Have a family history of diabetes
  • Gave birth to a baby that weighed more than 9 pounds or had a birth defect
  • Have high blood pressure
  • Have too much amniotic fluid
  • Have had an unexplained miscarriage or stillbirth
  • Were overweight before your pregnancy
  • Gain too much weight during your pregnancy
  • If you are a smoker
  • Have polycystic ovarian syndrome

Signs and Symptoms:

Most of the time there are no symptoms. The diagnosis is made during a routine prenatal screening.

When symptoms are present they may include:

  • Blurred vision
  • Fatigue
  • Frequent infections, including those of the bladder, vagina, and skin
  • Increased thirst
  • Increased urination
  • Nausea and vomiting
  • Weight loss despite increased appetite


Shoulder dystocia in Gestational Diabetes

  • Preterm birth
  • Fetal Macrosomia, which can lead to shoulder dystocia (fetus’s shoulder gets stuck under the pubic symphysis during delivery)
  • Birth injuries  (e.g. Erb’s palsy)
  • Neonatal hypoglycemia
  • Neonatal hypocalcemia
  • Increase in congenital anomalies
  • Hyperviscosity due to polycythemia
  • Hyperbilirubinemia
  • Infant respiratory distress syndrome
  • Caudal regression syndrome


Gestational diabetes is routinely screen between 24 & 28 weeks of gestational age.

  • First: Glucose Load, which consists of  non-fasting ingestion of 50 gram of glucose, with a measurement of serum glucose one hour later. If the serum glucose is above 14 mg/dL, then glucose tolerance test is done next.
  • Second: Glucose Tolerance Test, which consists of ingestion of 100 mg of glucose after fasting, with 3 measurements of serum glucose at 1, 2 and 3 hours. If any of the serum glucose measurements are elevated, gestational diabetes is confirmed. The following are the values which the American Diabetes Association considers to be abnormal during the 100 g of glucose OGTT:
    • Fasting blood glucose level ≥95 mg/dl (5.33 mmol/L)
    • 1 hour blood glucose level ≥180 mg/dl (10 mmol/L)
    • 2 hour blood glucose level ≥155 mg/dl (8.6 mmol/L)
    • 3 hour blood glucose level ≥140 mg/dl (7.8 mmol/L)
Routine Monitoring During Pregnancy:
  • HbA1c in each trimester
  • Triple-marker screen in 2nd trimester to assess for neural tube defects (NTD)
  • Monthly sonograms to assess fetal macrosomia or Intrauterine Growth Retardation (IUGR)
  • Monthly biophysical profiles
  • Start weekly nonstress test (NST) and amniotic fluid index (AFI) at 32 weeks if taking insulin, macrosomia, previous stillbirth or hypertension
  • Start NSTs and AFIs at 26 weeks if small vessel disease is present or there is poor glycemic control.



Most women can manage their GDM with dietary changes and exercise. Self monitoring of blood glucose levels can guide therapy. Some women will need antidiabetic drugs, most commonly insulin therapy.

Any diet needs to provide sufficient calories for pregnancy, typically 2,000 – 2,500 kcal with the exclusion of simple carbohydrates. The main goal of dietary modifications is to avoid peaks in blood sugar levels.


If monitoring reveals failing control of glucose levels with these measures, or if there is evidence of complications like excessive fetal growth, treatment with insulin might be necessary. This is most commonly fast-acting insulin given just before eating to blunt glucose rises after meals. Care needs to be taken to avoid low blood sugar levels due to excessive insulin.

There is some evidence that certain oral glycemic agents might be safe in pregnancy, or at least, are less dangerous to the developing fetus than poorly controlled diabetes. The oral medication metformin is better than glyburide. While metformin and insulin if needed may be better than just insulin.

Metformin being available by mouth oral is preferred to injections. Treatment of polycystic ovarian syndrome with metformin during pregnancy has been noted to decrease GDM levels.
References for Gestational Diabetes:

-Fischer, C. (2rd edition). (2013). Master the boards USMLE step 2. New York: Kaplan Publishing.
-Fischer, C. (3rd edition). (2012). Master the boards USMLE step 3. New York: Kaplan Publishing.


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