Carrie Madormo, RN, MPH, is a freelance health writer with over a decade of experience working as a registered nurse in a variety of clinical settings.
Peter Weiss, MD, is a board-certified OB/GYN and expert in women's health.
Insulin is a hormone the pancreas produces to help control blood glucose levels. Insulin may be needed to manage existing diabetes (type 1 or type 2) during pregnancy or, in some instances, to control blood sugar caused by gestational diabetes.
Insulin does not cross the placenta and is considered safe during pregnancy. It can be administered by injection through a syringe, insulin pen, or insulin pump. Pregnant individuals need to receive diabetes treatment.
This article provides an overview of how to use insulin during pregnancy, including when it is needed, how to administer it, and possible pregnancy complications from high blood glucose levels.
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Every time we eat, our bodies digest food, releasing glucose into the blood. Our cells then use glucose for energy. Insulin is the hormone that allows glucose to enter cells. When our bodies are not producing or using insulin, blood glucose levels remain high because glucose cannot enter the cells.
People with type 1 and type 2 diabetes often need to take insulin to control their blood glucose levels. Insulin may also be required to treat gestational diabetes.
Insulin is available dissolved or suspended in liquid form. The most common strength of insulin in the United States is 100 units per milliliter of fluid (U-100).
There are several types of insulin, and your healthcare provider will discuss the right fit for you. Common types of insulin include:
Possible complications of uncontrolled blood sugar during pregnancy include:
Most healthcare providers recommend people with type 1 diabetes reach their A1C goal for at least a few months before planning to become pregnant to make it easier to manage their blood glucose levels. Because of hormonal changes during pregnancy, your body’s need for insulin will change.
Blood glucose levels may increase during labor and then drop right after childbirth. For most pregnant people with type 1 diabetes, delivering your baby in a hospital is the safest option.
Not everyone with type 2 diabetes requires insulin every day. Your diabetes care plan may include diet changes, daily physical activity, blood glucose monitoring, oral medications, and insulin injections.
The body’s need for insulin usually increases during pregnancy, especially during the last three months. This increased need is caused by the hormones the placenta makes.
Your insulin dose and schedule will depend on your blood glucose levels and could change throughout your pregnancy.
People with gestational diabetes did not have diabetes before pregnancy. It is caused by hormonal changes and weight gain that happen with pregnancy. Every year about 2–10% of all pregnancies in the United States are affected by gestational diabetes.
Most pregnant people are screened for gestational diabetes around 24–28 weeks of pregnancy. It is important to address gestational diabetes immediately because about 50% of those with gestational diabetes will develop type 2 diabetes after pregnancy. Gestational diabetes is often treated with a healthy diet, daily physical activity, and blood glucose monitoring.
Many people with gestational diabetes do not require insulin. If your blood glucose levels are consistently high despite lifestyle changes, your healthcare provider may recommend insulin treatment.
It is safe to take insulin during pregnancy. However, side effects are possible. Research shows that insulin may cause the placenta to grow larger and heavier throughout pregnancy.
When a pregnant person takes insulin, their blood glucose level goes from high to low. This change may trigger the baby’s body to release more insulin. Over time, this can lead the baby to grow more and be considered large for gestational age (LGA).
Though side effects of insulin are possible, they are considered safer than the possible complications of hyperglycemia. Controlling blood glucose levels during pregnancy is essential to a healthy pregnancy and baby.
Insulin is not the only approved diabetes treatment for pregnant people. Other options include diet, exercise, and oral medications.
Diet and exercise are essential parts of the treatment plan for anyone with diabetes. For many people with gestational diabetes, these are the only treatments needed to control their blood glucose levels.
When you are diagnosed with diabetes, your healthcare provider will likely recommend meeting with a dietitian to develop an eating plan. Healthy food choices include vegetables, fruits, whole grains, lean proteins, and healthy fats. People with diabetes should limit their daily fat intake to 30% or less of their daily calories.
Daily physical activity is another way to manage blood glucose levels. Exercise helps to use up the extra blood sugar for energy. It also relieves stress, strengthens muscles, improves pregnancy aches, and lowers the risk of developing type 2 diabetes in the future. Talk with your healthcare providers about an exercise plan. Low-impact activities that may feel good include walking, swimming, and cycling.
Diabetes medications are common treatments for type 1 and type 2 diabetes. These oral medications cross the placenta, so they may affect the baby. Talking with your healthcare provider about the risks and potential benefits of oral medications is important.
Diabetes medications for pregnancy include:
A study found that metformin was not as well tolerated by pregnant people as glyburide. Side effects of metformin include nausea, vomiting, and diarrhea.
Insulin may be necessary during pregnancy to treat type 1, type 2, or gestational diabetes. Insulin is safe to take during pregnancy and does not cross the placenta. Keeping blood glucose levels in a normal range is essential to a healthy pregnancy and baby. Possible complications of hyperglycemia during pregnancy include birth defects, large fetal size, C-section, preterm birth, preeclampsia, and pregnancy loss. Other diabetes treatments include diet, exercise, and oral medications.
Managing a diabetes diagnosis is stressful anytime, but pregnancy adds a new layer of complication. It may help to remember that people with type 1, type 2, or gestational diabetes can have safe pregnancies and healthy babies. The goal of treating diabetes during pregnancy is to keep blood glucose levels in the safe range for the pregnant person and the baby. Talk with your healthcare team about your treatment plan and don’t hesitate to ask questions.
No, insulin does not cross the placenta. When diet and exercise alone are ineffective at managing diabetes during pregnancy, insulin is usually the next step.
Pregnant people have high blood glucose levels (hyperglycemia) over time, and their babies can grow larger than they usually would. Taking insulin can help to keep blood glucose levels stable and reduce the risk of having a baby who is large for gestational age (LGA). However, pregnant people who take insulin may still give birth to larger babies. Work with your healthcare team to make a delivery plan.
American Diabetes Association. Prenatal care.
American Diabetes Association. Insulin basics.
Centers for Disease Control and Prevention. Types of insulin.
Centers for Disease Control and Prevention. Type 1 or type 2 diabetes and pregnancy.
Centers for Disease Control and Prevention. Type 1 diabetes and pregnancy.
Centers for Disease Control and Prevention. Gestational diabetes.
American Diabetes Association. How to treat gestational diabetes.
Arshad R, Karim N, Ara Hasan J. Effects of insulin on placental, fetal and maternal outcomes in gestational diabetes mellitus. Pak J Med Sci. 2014;30(2):240-244. doi:10.12669/pjms.302.4396
American Diabetes Association. How to treat gestational diabetes.
National Institute of Diabetes and Digestive and Kidney Diseases. Managing & treating gestational diabetes.
Thorkelson SJ, Anderson KR. Oral medications for diabetes in pregnancy: Use in a rural population. Diabetes Spectr. 2016;29(2):98-101. doi:10.2337/diaspect.29.2.98
Carrie Madormo, RN, MPH, is a health writer with over a decade of experience working as a registered nurse. She has practiced in a variety of settings including pediatrics, oncology, chronic pain, and public health.
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