Dietary Guidelines – Gestational Diabetes

Dietary Guidelines:

The first and the most important step in the management of Gestational Diabetes Mellitus (GDM) is to refer the patient for medical nutritional counseling and diabetes self-management coaching through a certified diabetes educator (CDE). 

Patient education should address the following topics:

• Dietary advice (focus on getting necessary nutrients)
• Monitor weight (to prevent excessive weight gain)
• Monitor BG (through glucometer or continuous glucose monitors/CGM)

Because of an increase in blood volume during pregnancy, normal BG and HbA1c values are lower in pregnant women compared to non-pregnant women. The goal of treatment in GDM is to keep BG (particularly after meals) near-normal state. Several studies have shown excellent outcomes in GDM patients if BG is near-normal during pregnancy. 

Target BG values are:

• Fasting BG <95 mg/dL
• 1- hour after meals <140 mg/dL 

Or

• 2 hours after meals <120 mg/dL

Calories: 

Women gain weight during pregnancy. The typical weight gain during normal pregnancy in a woman with an average weight is about 25 to 35 lbs. During the first trimester, weight gain is about 2-4 lbs. and subsequently it is about 0.8 to 1 lb. /week. 

This weight gain will require eating about 300 extra calories/per day in the second, and about 500 extra calories/per day during the third trimester. In an average woman, this would mean about 1800 to 2200 calories per day 

Carbohydrates:

Carbohydrates are one of the three macronutrients and are the main source of glucose – the most important source of energy in humans. The carbohydrates in our diets have the most significant effect on blood glucose (BG) levels. For many women with GDM, we recommend that the total daily carbohydrate intake be about 175 to 210 grams. 

As morning BG is higher in most pregnant women, eat a smaller amount of carbohydrates at breakfast. After that, spread your carbohydrates throughout the day. Eating smaller amounts of carbohydrates at regular intervals throughout the day will keep your BG from rising after you eat. 

 A typical meal plan may look like this:

Breakfast: 1-2 carbohydrate servings

Lunch and Dinner: 3-4 carbohydrate servings

Snacks (2 to3): 1 or 2 carbohydrate servings

For meals, we recommend that you choose ‘good carbs’ – starches like vegetables and whole grains, and avoid ‘bad carbs‘ such as desserts, ice cream, canned fruit with syrup, cookies, cakes, candy, and sugary cereals. 

Some other examples of good sources of carbohydrates are:

• One cup of starch such as whole grain pasta or brown rice: approximately 45 grams. 
• 2 slices of whole grain bread: about 12-15 grams each
• One medium bagel: 40-50 gram
• Oatmeal – cooked: 20 grams per cup.
• One English muffin: 30 grams.
• ½ cup of beans: ½ cup of black beans is about 12 grams. 
• A small starchy vegetable: a smallpotato is about 15 grams.  
• One small fruit, half of a large fruit, or a half cup of mixed fruits: 15 grams of carbohydrate. 
• 8 oz. of low-fat, fortified milk: 15 grams.
• One small apple: 15 grams
• One cup of berries: 15 grams 

Fruits are high in natural sugars. You may have one to three servings of fruits per day, but eat only one fruit serving at a time. Avoid fruit juices.

Because you will eat fewer calories from carbohydrates with meals, try to have 2 or 3 healthy snacks per day to fulfill your daily nutritional needs. Healthy snacks may include Greek yogurt, nuts, whole grain crackers with cheese, and peanut butter with carrots or apples.

Fiber:

Increase your fiber intake to 25-30g daily. Fiber slows down the rate at which the body absorbs carbohydrates and reduces appetite. Include proteins and healthy (unsaturated) fats in your meals and snacks. They may also even out your BG and reduce hunger.

It is best to work with your dietitian to determine an appropriate meal plan for you. You will find it easier to make your meal plans if you can learn to estimate serving sizes and carbohydrate counting (see our videos on Carbohydrates and Fats for further details).  

Here is an example of a 3-day meal plan:

Exercise Guidelines:

Moderate exercise should be a part of the treatment plan for patients who have no medical or obstetric contraindications to exercise. In general, walking, jogging, bicycling, and swimming is safe, while activities that may carry a risk of abdominal trauma or falls (such as gymnastics, soccer, etc.) should be avoided. Ask your physician about his/her recommendations, based on your case.

Medications:

Lifestyle changes such as diet and exercise can successfully control GDM in 90-95% of patients. If BG targets are not achieved rather quickly, you may need to take medication(s). Insulin is considered the safest and most effective treatment of GDM. It has no side effects except the risk of hypoglycemia or low BG, which is fortunately uncommon in patients with GDM. 

Depending on your BG pattern, you may have to take one to four insulin injections daily. 

In the US, FDA has approved the following insulin preparation for use during pregnancy:

• Fast or rapid-acting: Novolog^® (Insulin Aspart), Humalog^® (Lispro Insulin)
• Regular Insulin (Humulin-R^® and Novolin-R^®)
• Slow-acting (Long or intermediate-acting): Levemir^® (Insulin Detemir) and NPH Insulin (Humulin-N^® and Novolin-N^®).

In some mild cases of GDM or when a patient refuses to take insulin injections, two oral medicines can be used in GDM – metformin and glyburide. Metformin is moderately effective, causes less weight gain in mothers, may lead to less macrosomia (large babies), and has a lower chance of low glucose in the newborn baby. However, 40% of the GDM patients who start metformin will eventually need insulin therapy. Glyburide may be used in some cases.

Delivery and follow-up:

If pregnancy progresses normally and there are no complications, the patient is allowed to continue pregnancy till the full term is reached or maybe induced at 38-39 gestational weeks. 

All diabetes medications including insulin are stopped when the patient is induced. During labor, the target BG is 70-95 mg/dL range. Sometimes patients may require dextrose (D5) infusion during active labor and occasionally low dose IV insulin infusion is needed. Most women do not need medications or Insulin after delivery. 

Because 50% of women with GDM may develop type 2 diabetes during the next 10 years, healthy eating and attention to weight control after delivery is encouraged. At 6-12 weeks after discharge, OGTT is recommended to identify those who have a higher risk of developing type 2 DM. This subset of women requires ongoing nutritional counseling and may be candidates for metformin and/or GLP-1 analog medicines, such as Ozempic^®, Trulicity^®, etc. In some cases, if the patient’s clinical presentation suggests insulin deficiency (and not insulin resistance), markers of type 1 diabetes (e.g. autoimmune markers like GAD-65 autoantibodies) are checked, and occasionally tests for maturity-onset diabetes of the young (MODY) are ordered.