Gestational Diabetes Mellitus, Diagnosis
Gestational Diabetes Mellitus, Diagnosis

Gestational Diabetes Mellitus, Diagnosis

Gestational diabetes mellitus, or gestational diabetes, is a form of diabetes that some women get during pregnancy. To control blood sugar (glucose) in the body, the pancreas makes a hormone called insulin. This hormone allows glucose to enter the cells in the body. The cells use glucose for energy. However, for some pregnant women, the pancreas may not make enough insulin or the body may not use available insulin properly. This leads to gestational diabetes.

Gestational diabetes lasts only a short time. It usually happens at weeks 24–28 of pregnancy and goes away after delivery. However, women who get gestational diabetes are more likely to:
  • Get it again if they become pregnant.
  • Develop type 2 diabetes in the future.

Gestational diabetes is not likely to cause problems if it is treated. If not controlled with treatment, it may cause problems during labor and delivery. Some problems can harm the baby and the mother.

What are the causes?

This condition occurs during pregnancy when the woman's body makes growth hormones that help the baby grow. Sometimes, these hormones:
  • Cause the pancreas to work harder than normal to make more insulin. Sometimes, the pancreas still cannot make enough insulin.
  • Cause insulin resistance. This makes it hard for the cells to use insulin properly.

Insulin resistance or lack of insulin causes extra glucose to build up in the blood instead of going into cells. This leads to high blood glucose (hyperglycemia).

What increases the risk?

This condition is more likely to develop in pregnant women who:
  • Are older than age 25 during pregnancy.
  • Have a family history of diabetes.
  • Are overweight.
  • Have had gestational diabetes in the past.
  • Have polycystic ovary syndrome (PCOS).
  • Are pregnant with twins or other multiples.

What are the signs or symptoms?

Common symptoms of this condition include:
  • Increased thirst.
  • Increased hunger.
  • Needing to urinate more often.

Most women do not notice these symptoms because the symptoms are similar to other symptoms of pregnancy.

How is this diagnosed?

This condition may be diagnosed based on your blood glucose level. This may be checked:
  • After you fast for 8 hours or longer (fasting blood glucose test, or FBG).
  • Any time of day, no matter when you eat (random glucose test).
  • At weeks 24–28 of pregnancy, to check how your body responds to glucose (oral glucose tolerance test, or OGTT).

If you have risk factors, you may be screened for type 2 diabetes at your first health care visit during your pregnancy.

How is this treated?

Treatment for this condition depends on the stage of your pregnancy and any other medical conditions you may have. Treatment may include:
  • Eating a healthy diet and getting more physical activity. These are the most important ways to manage gestational diabetes.
  • Checking your blood glucose as often as told.
  • Taking insulin or other diabetes medicines every day. These medicines will be prescribed only if needed.

You may need to work with a diabetes specialist, or endocrinologist, on a treatment plan. The goal of treatment is to have the right blood glucose levels during your pregnancy. The levels are checked while you are fasting and after you eat. Your health care provider will tell you what those levels are.

Follow these instructions at home:

Learn about your condition

Learn as much as you can about your condition. Ask your health care provider:
  • How often should I check my blood glucose, and where do I get the equipment?
  • What diabetes medicines do I need, and when should I take them?
  • Do I need to meet with a certified diabetes care and education specialist?
  • What number can I call if I have questions?
  • Where can I find a support group for people with gestational diabetes?

General instructions

  • Take over-the-counter and prescription medicines only as told by your health care provider.
  • Manage your weight gain during pregnancy. Your expected weight gain depends on your BMI (body mass index) before pregnancy.
  • Drink enough fluid to keep your urine pale yellow.
  • Carry a medical alert card or wear medical alert jewelry that says you have gestational diabetes.
  • Keep all follow-up visits. This is important.

Where to find more information

Contact a health care provider if you:

  • Have a blood glucose level at or above:
    • 240 mg/dL (13.3 mmol/L).
    • 200 mg/dL (11.1 mmol/L), and you have ketones in your urine. Ketones are made by the liver when a lack of glucose forces the body to use fat for energy.
  • Have a fever.
  • Have been sick for 2 days or more and are not getting better.
  • Have either of these problems for more than 6 hours:
    • Vomiting every time you eat or drink.
    • Diarrhea.

Get help right away if you:

  • Become confused or cannot think clearly.
  • Have trouble breathing.
  • Have moderate or high ketone levels in your urine.
  • Feel that your baby is moving around less than usual.
  • Develop unusual discharge or bleeding from your vagina.
  • Start having early (premature) contractions. Contractions may feel like a tightening in your lower abdomen.
  • Have a severe headache.

These symptoms may represent a serious problem that is an emergency. Do not wait to see if the symptoms will go away. Get medical help right away. Call your local emergency services (911 in the U.S.). Do not drive yourself to the hospital.


  • Gestational diabetes mellitus is a form of diabetes that some women get during pregnancy. It usually happens at weeks 24–28 of pregnancy and goes away after delivery.
  • Treatment may include eating a healthy diet and getting more physical activity. You may also be given insulin or other diabetes medicines.
  • Contact a health care provider if your glucose levels reach 240 mg/dL (13.3 mmol/L) or higher.
  • Get help right away if you become confused or cannot think clearly, or you feel that your baby is moving around less than usual.

This information is not intended to replace advice given to you by your health care provider. Make sure you discuss any questions you have with your health care provider.