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Diabetes in Pregnancy

Pregestational Diabetes

All women with pre-existing type 1 or type 2 diabetes should receive preconception care to optimize glycemic control, assess complications, review medications and begin folate supplementation.

Suboptimal sugar control is associated with several adverse outcomes in pregnancy including

  • Preeclampsia
  • Hydramnios
  • Macrosomia and large for gestational age infant
  • Fetal organomegaly (hepatomegaly, cardiomegaly)
  • Maternal and infant birth trauma
  • Operative delivery
  • Perinatal mortality
  • Neonatal respiratory problems and metabolic complications (hypoglycemia, hyperbilirubinemia, hypocalcemia, erythremia)

Gestational Diabetes Mellitus (GDM)

Gestational diabetes mellitus (GDM) is a condition that develops during pregnancy when the body is not able to make enough insulin. The lack of insulin causes the blood glucose (also called blood sugar) level to become higher than normal. Gestational diabetes affects between 2 and 10 percent of women during pregnancy.

All women will be screened for gestational diabetes with a 1hr glucose challenge between 24-28 weeks of pregnancy. Expect to stay at the lab for one hour. This does not have to be done in the fasting state. This can either come back normal, or make the diagnosis of diabetes or lead to further testing to clarify.

If you are at high risk for developing GDM, your doctor will screen you earlier than 24-28 weeks of pregnancy.

Untreated GDM leads to increased maternal and perinatal morbidity, while treatment is associated with outcomes similar to control populations.

Complications of gestational diabetes can include:

  • Having a large baby (weighing more than 9 lbs or 4.1 kg), which can increase the risk of injury to the mother or baby during delivery and increase the chance of needing a cesarean section
  • Preeclampsia

After you are diagnosed with gestational diabetes, you will need to make changes in what you eat, and you will need to learn to check your blood sugar level. In some cases, you will also need to learn how to give yourself insulin injections or take medications.

The main goal of treatment for gestational diabetes is to reduce the risk that the baby will be large (weigh greater than 9 lbs at birth). A large baby can be difficult to deliver through the pelvis (called “shoulder dystocia”). A vaginal delivery increases the risk of injuring a large baby (eg, broken bones or nerve injury). A large baby is also more likely to cause injury to the mother during the delivery.

You are more likely to have a large baby if your blood sugar levels are higher than normal during pregnancy.

Changes in diet — The following are some general dietary recommendations:

  • Avoid high-calorie snacks and desserts, including soda with sugar, fruit punch, candy, chips, cookies, cakes, and full-fat ice cream
  • You can use artificial sweeteners, such as aspartame (Nutrasweet), sucralose (Splenda), stevioside (Stevia), or acesulfame potassium (Sunnet). These sweeteners have not been linked to an increased risk of birth defects.
  • Eat a lot of vegetables and fruits, at least five servings a day. Some fruits (like grapes, dried fruit) can increase your blood sugar level excessively and should be eaten in limited amounts. Don’t eat a lot of starchy vegetables (eg, potatoes), but eat as many non-starchy fruits or vegetables as you like.
  • Choose foods with whole grains. This includes whole-wheat bread, brown rice, or whole-wheat pasta instead of white bread, white rice, or regular pasta.
  • If you eat red meat, choose lean cuts of meat that end in "loin" (eg, pork loin, tenderloin, sirloin). Remove skin from chicken and turkey before eating.
  • Choose low- or fat-free dairy products, such as skim milk, nonfat yogurt, and low-fat cheese
  • Use liquid oils (olive, canola) instead of solid fats (butter, margarine, shortening) for cooking

Blood sugar monitoring — You will learn how to check your blood sugar level and record the results.

Initially, most women should check their blood sugar level four times per day:

  • Before eating in the morning
  • One hour after breakfast, lunch, and dinner

This information can help to determine whether your blood sugar levels are on target. If your levels stay higher than they should be, your doctor will probably recommend that you start using insulin.

Exercise — Although exercise is not a necessary part of gestational diabetes treatment, it might help to control blood sugar levels. If you were exercising before, you should continue after being diagnosed with gestational diabetes.

If you did not previously exercise, ask your doctor or nurse if exercise is recommended. Most women who do not have medical or pregnancy-related complications are able to exercise, at least moderately, throughout their pregnancy.

Metformin – Safe in pregnancy (up to 2.5 g daily) and most often controls blood sugars adequately. Preferred 3:1 by women compared to insulin. The goal is to keep sugars between 4 and 8mmol/L. Almost half of the time, insulin will need to be added to keep sugars under control.

Insulin — Approximately 15 percent of women with gestational diabetes will require insulin. Insulin is a medicine that helps to reduce blood sugar levels and can reduce the risk of gestational diabetes-related complications. Insulin is the most common medicine for treating gestational diabetes.

You must give insulin by injection because it does not work when it is taken by mouth. Most women start by giving one shot of insulin per day. If your blood sugar levels are high after eating, you may need to give a shot two or three times per day. This information will be given by your physician Keeping accurate records helps to adjust insulin doses and can decrease the risk of complications.


Prenatal visits — Most women who develop gestational diabetes have more frequent prenatal visits (eg, once every week or two), especially if insulin is used. The purpose of these visits is to monitor your and your baby's health, discuss your diet, and adjust your dose of insulin to keep your blood sugar levels near normal. It is common to change the dose of insulin as the pregnancy progresses.

Nonstress testing — You may need tests to monitor the health of the baby during the last trimester of pregnancy, especially if your blood sugars have been high, you are using insulin, or if you have any pregnancy-related complications (eg, high blood pressure). The most commonly used test is the nonstress test done at the hospital.


If your blood sugar levels are close to normal during pregnancy and you have no other complications, the ideal time to deliver is between 39 and 40 weeks of pregnancy. If you do not deliver by your due date, you may need additional testing to monitor your and your baby's health. In most women with a normal-size baby, there are no advantages to a cesarean delivery over a vaginal delivery.

Your blood sugar levels will be monitored during labour. Most women have normal blood sugar levels during labour and don’t need any insulin. Insulin is given if your blood sugar level becomes high. High blood sugar levels during labour can cause problems in the baby, both before and after delivery.


After delivery, most women with gestational diabetes have normal blood sugar levels and do not require further treatment with insulin. You can return to your prepregnancy diet, and you are encouraged to breastfeed.

However, it is important to check your blood sugar level the day after delivery to be sure that it is normal or near normal. Pregnancy itself does not increase the risk of developing type 2 diabetes. However, having gestational diabetes does increase your risk of developing type 2 diabetes later in life. The risk of developing type 2 diabetes is greatly affected by body weight. Women who are obese have a 50 to 75 percent risk of type 2 diabetes, while women who are a normal weight have a less-than-25 percent risk. If you are overweight or obese, you can reduce your risk of type 2 diabetes by losing weight and exercising regularly.

If your blood sugar level is normal after delivery, you should have testing for type 2 diabetes at six weeks postpartum. Testing usually includes a two-hour glucose tolerance test (GTT).

Risk of recurrent gestational diabetes — One-third to two-thirds of women who have gestational diabetes in one pregnancy will have it again in a later pregnancy.

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