Written by Lauren Ranley, MS, RD
Gestational diabetes (GDM) is insulin resistance identified during pregnancy that typically resolves after pregnancy. Have you received a gestational diabetes diagnosis? Let’s explore how a predominantly plant-based diet (mainly a diet high in fiber and low in saturated fat) effectively manages blood sugar in individuals with GDM. Be sure to consult your physician before starting any new diet plan.
What is Gestational Diabetes?
During pregnancy, glucose passes through the placenta and is the preferred energy source for the fetus. In later stages of pregnancy, free fatty acids (FFA), or lipids, are primarily used for maternal energy, allowing glucose to be used by the fetus. During the first trimester, maternal glucose levels are lower than in non-pregnant women. The second and third trimesters are characterized by increased hormone levels (progesterone and human placental lactogen). Progesterone stops the insulin signaling from fat cells, and human placental lactogen acts directly on insulin receptors, preventing insulin from binding, i.e., insulin resistance.  This increase in insulin resistance has a purpose — to make more glucose available for the fetus. In individuals with GDM, the pancreas cannot produce enough insulin to compensate for the increased insulin resistance.
Blood Sugar Targets for Gestational Diabetes
The American Diabetes Association suggests the following targets for individuals diagnosed with gestational diabetes . Please note that these are general recommendations, and your doctor may recommend more or less strict goals.
- Before a meal (fasting): 95 mg/dl or less
- One hour after a meal (postprandial): 140 mg/dl or less
- Two hours after a meal (postprandial): 120 mg/dl or less
Risks of Unmanaged Gestational Diabetes
Strict blood sugar management while pregnant decreases the risk of adverse outcomes for both mother and baby. Unmanaged gestational diabetes increases the chances of:
- Fetal Macrosomia, infants larger than average (> 8lbs 13 oz)
- Premature Birth, birth occurring before 37 weeks of gestation
- Hypoglycemia at Birth, infant's glucose levels are too low at birth
- Neonatal Jaundice, a liver condition causing yellowing of the skin and eyes
Children born to mothers with gestational diabetes and obesity have an increased risk of developing insulin resistance and being overweight as they age. 
Mothers with GDM are at an increased risk of recurrence in subsequent pregnancies and developing type 2 diabetes in the future. GDM can also mask undiagnosed type 1 or type 2 diabetes, with diabetes symptoms appearing during pregnancy.  Complications due to unmanaged GDM include accelerated diabetic retinopathy, which may regress after delivery, diabetic nerve pain, high blood pressure, and polyhydramnios or excessive amniotic fluid.
Lifestyle Changes for GDM Blood Sugar Management
Research supports a plant-forward diet for the management of blood sugar in GDM. A plant-forward diet includes an abundance of high-fiber foods, like fresh fruits and vegetables, whole grains, legumes, nuts, and seeds, while limiting fat intake to 30% or less of daily calories.  Note that a plant-forward diet does not completely exclude animal products; meat and dairy products can still be consumed more mindfully. A great example of a plant-forward diet is the Mediterranean diet.
What makes a plant-forward diet beneficial, specifically during pregnancy? A diet high in polyphenols, a group of phytochemicals found in plants, positively affects individuals diagnosed with GDM. Polyphenols are found in vegetables, fruits, legumes, seeds, nuts, and cereals.  Research supports plant-based diets and diets supplemented with additional phytochemicals as having a beneficial impact on glycemic control, reduced oxidative stress (a process that can cause cell damage) associated with GDM, and improved pregnancy outcomes.  To ensure adequate intake of phytochemicals, include a variety of plant-based foods in your diet.
GDM vs. T2D
Whether an individual has gestational diabetes or type 2 diabetes, the goal is the same — manage blood sugar levels and reduce associated risks. So what’s the difference between recommendations for GDM versus T2D?
A plant-forward diet and appropriate physical activity are suitable for both T2D and GDM (unless specified otherwise by your doctor). However, in individuals with GDM, blood sugar ranges are much stricter, given the added risks discussed above. Weight loss may be appropriate for those with T2D but is not typically recommended during pregnancy. Complex carbohydrates and fiber-rich foods are highly encouraged for both T2D and GDM. However, for individuals with T2D, the general recommendation is to consume moderate amounts of carbohydrates consistently daily. Carbohydrate recommendations for GDM are less flexible and outlined below:
- Breakfast: 15-45 g
- Lunch: 45-75 g
- Dinner: 45-75 g
- Snacks: 15-45 g
The need for certain nutrients and calories increases as pregnancy progresses, so following a well-balanced diet is essential. To support a healthy pregnancy and properly manage blood sugar levels, find a nutrient-dense, plant-forward diet that works best for you.
Exercise allows the body to use glucose without extra insulin and combats insulin resistance. Always check with your doctor before starting an exercise program, especially while pregnant.  Aim for 30 minutes of daily physical activity, including walking, swimming, stationary cycling, low-impact aerobics, and strength training. Break up the exercise into manageable sessions. For example, complete two 15-minute walks or do a 10-minute walk, 10-minute strength training, and 10-minute prenatal yoga. As pregnancy progresses, perform exercises within your abilities.
Let's Recap: How to Manage Gestational Diabetes with a Plant-Based Diet
- Gestational diabetes is insulin resistance identified during pregnancy.
- A plant-forward diet, low in saturated fat and high in fiber and polyphenols, is beneficial for managing gestational diabetes.
- Exercise and physical activity allow the body to use glucose without needing more insulin.
- Blood sugar ranges are stricter with gestational diabetes than with type 2 diabetes.
- Nutrient and calorie needs change during pregnancy and should be considered when making food choices.