Obstetrics & Gynecology

Last updated on: October 19th, 2023

Hi there!

You’re looking at a short reference article from Explain Medicine (one of four distinct learning formats available in Clinical Odyssey). Try it out, and have fun improving your clinical skills.

Gestational diabetes mellitus

Clinicals - History


Gestational diabetes mellitus (GDM) is a condition in which a non-diabetic woman develops chronic hyperglycemia during pregnancy. This hyperglycemia, in most cases, is the result of impaired glucose tolerance secondary to pancreatic β-cell dysfunction, in a background of chronic insulin resistance or diminished insulin production. GDM tends to develop during the second or third trimester. It is most often diagnosed during the universal screening for GDM conducted at 24-28 weeks of gestation.

Risk factor: age

A maternal age ≥40 years is associated with an increased risk of impaired glucose tolerance during pregnancy.

Risk factor: ethnicity

Women of African-American, Hispanic, Middle-Eastern, Native American, Pacific Islander, and South Asian origin are more likely to develop GDM.

Risk factor: past GDM

Around one-third of women with GDM develop the condition in a future pregnancy.

Risk factor: positive family history

The presence of a first-degree relative with diabetes mellitus or a sister with GDM increases the risk of developing GDM.

Risk factor: sedentary lifestyle

An inactive lifestyle and westernized diet are both modifiable risk factors for GDM.

Risk factor: dysglycemic medications

Regular treatment with corticosteroids, antipsychotics, or other medications with an anti-insulin effect is another modifiable risk factor for GDM.

Risk factor: high gestational weight gain

During the period of gestation, a maternal weight gain >22 lb/year (>10kg/year) confers a more than two-fold increased risk for GDM.

Risk factor: weight before pregnancy

Pre-pregnancy obesity increases the risk for GDM.

Risk factor: High neonatal weight in a previous pregnancy

Previously delivering a baby >9 lb (4 kg) increases the risk for GDM.

Want to continue reading?

Subscribe to Clinical Odyssey today.
  • Enjoy unlimited access to 700+ learning modules.
  • Safely improve your skills, anytime and anywhere.
  • Get answers to your follow-up questions from practicing physicians.
Learn more ➜