Preexisting diabetes

What is preexisting diabetes?

Diabetes is a condition where blood sugar (glucose) levels are too high. Preexisting diabetes (also called pregestational diabetes) means you had diabetes before becoming pregnant. This is different from gestational diabetes, which is a kind of diabetes that some women get during pregnancy. 

In the United States, about 1 to 2 percent of pregnant women have preexisting diabetes and this number has increased in recent years.

When you have diabetes, your body doesn’t make enough insulin or can’t use insulin well, so you end up with too much sugar in your blood. This can cause serious health problems, including heart disease, kidney failure and blindness. High blood sugar can be harmful to your baby during the first few weeks of pregnancy when major organs, like the brain, heart, kidneys and lungs are forming.

There are two types of preexisting diabetes. Managing them before and during pregnancy can help reduce your risk of complications:

• Type 1 diabetes. This is when your body doesn’t make insulin. This is because your immune system destroys the cells in your pancreas that make insulin. People with type 1 diabetes must take insulin daily. 
• Type 2 diabetes. This is the most common type. If you have type 2 diabetes, your body makes insulin but doesn’t make or use it well. . It can be managed with lifestyle changes, medicine, and sometimes insulin.

Can preexisting diabetes cause problems during pregnancy?

If it’s not managed well, diabetes can increase your risk for complications, including:

• Birth defects, like heart defects and birth defects of the brain and spine called neural tube defects (also called NTDs).
• Cesarean birth (C-section). Diabetes increases the risk of having a large baby (macrosomia), which may require a c-section.
• High blood pressure and preeclampsia. These conditions can cause serious problems for a pregnant person and their baby.
• Problems with growth: Babies may be too large (macrosomia) or too small (fetal growth restriction).
• Pregnancy loss: Increased risk of miscarriage (loss before 20 weeks) and stillbirth (loss after 20 weeks).
• Preterm birth. Early birth before 37 weeks of pregnancy can lead to health issues.
• Shoulder dystocia or other birth injuries (also called birth trauma). Large babies may have a hard time passing through the birth canal, increasing the risk of injuries.

Most babies born to people with preexisting diabetes are healthy, but preexisting diabetes can increase the baby’s risk for:

• Low blood sugar (hypoglycemia) after birth.
• Breathing problems, including respiratory distress syndrome (RDS).
• Jaundice (a condition that causes yellow skin and eyes).
• Obesity (being very overweight) and type 2 diabetes later in life.

How can I manage diabetes before pregnancy?

Plan ahead so you’re as healthy as you can be before you get pregnant. Here’s what you can do:

• Control blood sugar levels for at least 3 to 6 months before pregnancy.
• Use birth control until your diabetes is under control and you’re ready to get pregnant.
• Take a multivitamin with 400 micrograms of folic acid in it every day. If you take it before pregnancy and during early pregnancy as part of healthy eating, it can help protect your baby from neural tube defects.
• Review medicine you take with your provider. It’s important to make sure the medicine is safe for your baby when you do get pregnant.
• Eat healthy and fresh foods as much as possible and do something active every day.

How can I manage diabetes during pregnancy?

Here’s what you can do to help manage your diabetes during pregnancy:

• Go to all your prenatal care checkups, even if you’re feeling fine.
• Follow your provider’s directions about how often to check your blood sugar.
• If you take insulin, take it exactly as your provider tells you to.
• Tell your providers about any medicine you take, even medicine that’s not related to your diabetes.
• Talk to your provider about taking low-dose aspirin. Low-dose aspirin (also called baby aspirin or 81 mg aspirin) can help prevent preeclampsia. You can start taking low-dose aspirin after 12 weeks of pregnancy (before 16 weeks is best).
• Check if your insurance covers a nutritionist or registered dietician. These are professionals that can help you learn what, how much and how often to eat to best control your diabetes.
• Ask your provider about labor and birth. Diabetes increases your chances for needing a c-section. If your provider thinks you need to have your baby by c-section, ask about timing. If your diabetes is well controlled, ask if it’s possible to wait until at least 39 weeks to have your baby.

To best manage your diabetes during pregnancy, you need a team of health care providers who work together to give you the best all-around care. Your team will include:

• Your prenatal care provider.
• An endocrinologist (a doctor who treats people with diabetes and hormone problems). 

Your team may also include other providers, including:

• A perinatologist (a doctor who treats high-risk pregnancies).
• A diabetes educator.
• A registered dietitian (also called RD). 
• Your baby’s healthcare provider, especially as you get closer to your baby’s birth.

How is preexisting diabetes treated during pregnancy?

If you have diabetes, you’ll need regular prenatal care to monitor your health and your baby’s growth. Your provider may recommend:

• Ultrasounds to check your baby’s growth and development.
• Nonstress tests and biophysical profiles. The nonstress test checks your baby’s heart rate. The biophysical profile is a nonstress test with an ultrasound.  
• Blood sugar monitoring and possible changes to your diet, medication, or insulin doses.
• A nutrition plan
• Considering low-dose aspirin after 12 weeks to help reduce the risk of preeclampsia (speak with your provider first)

During labor and birth, your provider watches your glucose level closely. Some people with diabetes require a c-section, but if diabetes is well-managed, vaginal birth is often possible.

If you have preexisting diabetes, is it OK to breastfeed?

Breastfeeding is safe and has many benefits for people with diabetes. It can help with your postpartum blood sugar control and provide important nutrients for your baby. If you breastfeed: 

• Work with a dietician or nutritionist to adjust your calorie intake.
• Monitor blood sugar closely.
• Talk to your provider about adjusting insulin doses as needed.

What are hypoglycemia and hyperglycemia?

Pregnancy affects how the body processes insulin. Some people may develop insulin resistance, meaning their body needs more insulin to control blood sugar. It is common for insulin needs to increase, especially in the third trimester.

Signs and symptoms of low blood sugar (hypoglycemia) include: 

• Dizziness, weakness, or shakiness
• Sweating and having a fast heartbeat
• Hunger or irritability (feeling cranky)

Signs of high blood sugar (hyperglycemia) include:

• Being thirsty
• Needing to urinate (pee) often
• Felling weak or tired
• Having blurred vision
• Having a yeast infection

Your provider can check you for these conditions during pregnancy to make sure you and your baby stay healthy. The good news is that by working with your healthcare team and following a diabetes care plan, you can improve the chances of a healthy pregnancy and baby.

Last reviewed: February 2025