Gestational Diabetes Testing

A. What it is

Screening for gestational diabetes that develops during pregnancy is a way to look for high blood sugar during pregnancy. You drink some very sweet liquid. Then you have a blood test to see how your body uses sugar (glucose). you will have a blood sample drawn from a vein, at pre determined timed intervals.

Gestational diabetes (GD) is a type of diabetes that can occur during pregnancy. It happens when your body isn't able to produce enough insulin to keep the amount of glucose (sugar) in your blood at safe and proper levels. If left untreated GD increases your likelihood of having a large baby, and can be associated with birth complications as well as health risks for the newborn (e.g., preeclampsia, shoulder dystocia). Untreated GD also increases the risk of stillbirth late in pregnancy (36-40 weeks). Women who develop GD are at higher risk of developing type 2 diabetes in the future. However, there is excellent treatment for GD, and most women diagnosed with GD have normal deliveries and healthy babies.

B. When it is done

If you're at an average risk of gestational diabetes, you'll likely have a screening test during your second trimester — between 24 and 28 weeks of pregnancy.

If you're at a high risk of diabetes — for example, if you're overweight or obese before pregnancy or if you have a mother, father, sibling or child with diabetes — your doctor may test for diabetes early in pregnancy, likely at your first prenatal visit.

All pregnant women should be offered blood glucose screening for GD between 24 and 28 weeks of pregnancy. If you have risk factors for GD, you will be tested earlier in your pregnancy. These risk factors include:

• Being older than 35

• Obesity (defined as a pre-pregnancy BMI greater than 30)

• Aboriginal, African, Asian, Hispanic, or South Asian ethnicity

• Family history of diabetes

• Polycystic ovarian syndrome or acanthosis nigricans

• Corticosteroid use during pregnancy

• Previous pregnancy with GD

• Previous delivery of a baby large than 4000 g

C. What the results mean

Results of the oral glucose tolerance test are given in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L).

Gestational diabetes

If you're being tested for gestational diabetes, your doctor will consider the results of each blood glucose test.

If your blood glucose level is higher than 140 mg/dL (7.8 mmol/L) after the one-hour test, your doctor will recommend the three-hour test. If your blood glucose level is higher than 190 mg/dL (10.6 mmol/L) after the one-hour test, you'll be diagnosed with gestational diabetes.

For the three-hour test:

• A normal fasting blood glucose level is lower than 95 mg/dL (5.3 mmol/L).

• One hour after drinking the glucose solution, a normal blood glucose level is lower than 180 mg/dL (10 mmol/L).

• Two hours after drinking the glucose solution, a normal blood glucose level is lower than 155 mg/dL (8.6 mmol/L).

• Three hours after drinking the glucose solution, a normal blood glucose level is lower than 140 mg/dL (7.8 mmol/L).

• If one of the results is higher than normal, you'll likely need to test again in four weeks. If two or more of the results are higher than normal, you'll be diagnosed with gestational diabetes.

If you're diagnosed with gestational diabetes, you can prevent complications by carefully managing your blood glucose level throughout the rest of your pregnancy.

D. Dietary changes

Eat regular, balanced meals and snacks.

Enjoy three meals and three snacks spaced evenly throughout the day.

Include at least three food groups in a meal and two food groups for a snack.

Eat one of your snacks at bedtime.

See Additional Resources for a sample meal plan.

A balanced diet contains foods with carbohydrates, protein and healthy fats. Carbohydrates raise your blood glucose levels. Read on to learn which carbohydrates are the healthiest choices for you.

Carbohydrate is found in grain products, fruit and fruit juice, some vegetables, milk and alternatives, dried beans, peas and lentils, and foods such as cakes, cookies, squares, candy and sugary drinks.

Choose fibre-rich sources of carbohydrates like whole grain breads and cereals, and dried beans, peas and lentils. Fibre slows carbohydrate absorption into your blood.

Choose vegetables and fruit rather than juice.

Choose low glycemic index (GI) foods more often. Low GI foods raise blood glucose at a slower rate than high GI foods. See Additional Resources for more details on the GI.

See the table below for recommended carbohydrate foods.

All types of carbohydrates except fibre raise your blood glucose.

Glucose is used in your body to give you and your baby energy.

Add foods that contain protein and small amounts of healthy fats at each meal and snack. Protein and fats slow carbohydrate absorption into your blood.

Choose protein sources that are lower in fat. See the table below for recommended protein foods.

Most protein foods do not raise your blood glucose because they have little or no carbohydrates.

Choose unsaturated fats instead of saturated or trans fats. See the table below for recommended fats and oils.

Fat does not raise your blood glucose because it has no carbohydrates. Unsaturated fats are the healthiest type of fat.

Recommended sources of carbohydrates, protein and fat

• Recommended Carbohydrate Foods

• Recommended Protein Foods

• Recommended Fats and Oils

• whole grain breads, pastas and cereals

• brown or wild rice

• whole grains like quinoa, barley, bulgur

• yam, sweet potato

• milk

• yogurt

• fruit

• dried beans, peas and lentils (also a protein source)

• lean cuts of chicken, beef, pork

• fish

• tofu

• eggs

• lower fat cheese (20% M.F. or less, cottage cheese)

• unsalted nuts and seeds, nut butters (also a healthy fat source)

• vegetable oils (canola, olive, soybean)

• non-hydrogenated margarine

• avocado

Foods that will not affect your blood sugar include:

• water;

• most vegetables;

• herbs and seasonings;

• mustard; and

• vinegar.

Limit foods that are high in sugar, fat, and/or salt.

These foods include cookies, cakes, donuts, chocolates, ice cream, chips, and deep-fried foods. If you choose to eat these foods, have a small portion or have some only on special occasions. Limit drinks like 100% fruit juice, pop and other sugary beverages (sweetened coffees and teas, cocktails, punches and drinks).

Drink water when you are thirsty.

Low fat (skim or 1%) milk is also a healthy choice.

Tea and coffee are safe during pregnancy.

See Additional Resources for information about caffeine and herbal teas during pregnancy.

Continue to follow general healthy eating guidelines for pregnancy.

Other Considerations

If you eat or drink foods or beverages made with sugar substitutes, do so in moderation so that they do not replace more nutritious foods or drinks.

Take a daily multivitamin that has:

0.4 mg (400 mcg) of folic acid (do not take more than 1 mg (1000 mcg) of folic acid per day);

16 to 20 mg of iron;

Vitamin B12.

Daily physical activity such as brisk walking, especially after meals, helps to control blood glucose.