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Diabetes during pregnancy

Gestational diabetes mellitus (GDM) is diabetes that occurs during pregnancy. A defining feature of diabetes is a high level of sugar in the blood (called blood glucose). 

  • Blood glucose rises when the body doesn’t produce enough of the hormone insulin, or when the body’s cells do not respond properly to insulin.
  • Insulin is needed to transport glucose from the blood into the cells, tissues and muscles, where it acts as ‘fuel’ to supply the energy our bodies need to function properly.
  • During pregnancy, the body produces extra hormones to support the needs of the fetus. 

This means the mother’s body needs three times more insulin.

If insulin production does not keep up, her blood glucose will rise and GDM will develop.

GDM can:

  • increase the mother’s risk of urinary tract infections
  • high blood pressure
  • giving birth by caesarean section.

The baby may also be at risk of:

  • weighing more than an ideal weight and suffering trauma at birth
  • having low blood glucose
  • experiencing prolonged newborn jaundice.

Should I be tested for GDM?

GDM affects three to five percent of all pregnant women. There is some debate in the medical community about whether all pregnant women should be tested. The Canadian Diabetes Association recommends in its most recent guidelines that all pregnant women be tested for GDM between 24 and 28 weeks of gestation. Women with risk factors should be tested even earlier – as early as the first trimester.

GDM risk factors:

  • Obesity
  • Age 35 years +
  • Family history of diabetes
  • GDM in a previous pregnancy

How do I manage GDM?  

The goal of treatment is to keep blood glucose as close to normal as possible. You may need to test your blood often, using a blood glucose meter. How often you must test and the type of treatment you need may vary throughout your pregnancy.

Nutrition Therapy

Nutrition therapy is the primary treatment for GDM. Women with GDM should be referred to a registered dietitian with expertise in diabetes management. Some tips include eating a wide variety of foods from all food groups to ensure adequate nutrition for optimal growth of the fetus, and controlled weight gain for the mother throughout the pregnancy.

Physical Activity

Being physically active helps control blood glucose and is encouraged as long as there are no pregnancy-related issues that affect the types of exercise that can be done safely. A brisk walk after meals is a great place to start.


If nutrition therapy and activity haven’t lowered your blood glucose after two weeks, you will need to take insulin by injection.

What are the long-term risks?

In most women, blood glucose levels return to normal after the birth of their baby. Up to 50 percent of women who have had GDM, however, are at risk of developing type 2 diabetes at some point later in their life. That’s why it’s very important to be tested within six months of the birth and at regular intervals throughout life.

Positive Lifestyle Changes

It may help to look at GDM as an opportunity to make healthy lifestyle choices you can continue. Women are highly motivated to take care of themselves during pregnancy to optimize their baby’s health.

Cynthia Lank is a freelance writer in Halifax, N.S., and was Executive Editor of the Canadian Diabetes Association 2003 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada.

a man carrying two children

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