Gestational Diabetes



Gestational diabetes mellitus (GDM) is diabetes that happens when a woman is pregnant. Diabetes is when there is a higher level of glucose in the blood than is normal. Insulin is a hormone that helps glucose move from the blood to the cells where it can be used for energy. Problems making or using insulin causes the glucose to build up in the blood. Hormones from the placenta can also block insulin from working as it should. The levels often return to normal after delivery.

Large Baby Due to Gestational Diabetes
Copyright © Nucleus Medical Media, Inc.


GDM is caused by reduced sensitivity to insulin during pregnancy.

Risk Factors

Women who are overweight or obese are at higher risk. It is also more common in older women and those who are Latino, Native American, Asian, Black, or Pacific Islander. Other things that may raise the risk are:

  • Family members with type 2 diabetes
  • Having GDM in the past
  • Heart disease
  • Low HDL ('good') cholesterol and high triglycerides
  • Polycystic ovary syndrome
  • Lack of activity



GDM often does not cause any symptoms. Those who do may have:

  • Increased urination
  • Thirst
  • Nausea
  • Weakness


GDM testing is done as part of routine prenatal screening at 24 to 28 weeks of pregnancy. It may be done earlier for women who are at high risk.

A woman does not need to fast before the glucose screening test. A special glucose drink will be given. Blood glucose levels will be tested 1 hour later to look for changes.

Women who have a high blood glucose screening test may need to have a 3-hour glucose tolerance test. She will not be able to eat or drink for 8 to 14 hours before the test. Blood will be drawn before the test. A special glucose drink will be given. Blood will be drawn every hour for 3 more hours to look for changes.



The goal of treatment is to return blood glucose levels to normal. This will help keep the mother and the baby healthy.

A blood glucose monitor will be used to check the levels throughout the day. The level will help plan meals, activities, and medicine. A woman's urine may also need to be tested for ketones. These are made when the body breaks down fat instead of carbohydrates for energy. Large amounts of ketones can lead to a problem called ketoacidosis. It can harm the woman and the growing baby.

GDM may be treated with:


A dietitian can help make a healthy meal plan. It will focus on eating 3 meals and 2 to 3 snacks per day. Carbohydrates can cause blood sugar to rise. A woman will be given a daily carbohydrate goal.


Physical activity can make it easier for the body to use glucose. Exercising 2.5 hours per week can help.


Some women may need insulin injections. Others may need to take anti-diabetes medicine.


The risk of GDM can be lowered with healthy lifestyle, such as:

  • Not smoking
  • Exercising
  • Eating healthy foods
  • Reaching a healthy weight before getting pregnant

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.

a (Diabetes, Gestational; GDM; Gestational Onset Diabetes Mellitus [GODM]; Glucose Intolerance During Pregnancy)


American College of Obstetricians and Gynecologists 

American Diabetes Association 


Canadian Diabetes Association 

Women's Health Matters 


American College of Obstetricians and Gynecologists Committee on Practice Bulletins—Obstetrics. Practice Bulletin No. 190: Gestational Diabetes Mellitus. Obstet Gynecol. 2018 Feb;131(2):e49-e64.

Gestational diabetes. American Diabetes Association website. Available at: Accessed January 14, 2020.

Gestational diabetes mellitus (GDM). EBSCO DynaMed website. Available at: . Updated December 18, 2019. Accessed January 14, 2020.