Pregestational diabetes, or preexisting diabetes, refers to a condition in which a person has diabetes (typically type 1 or type 2 diabetes) before becoming pregnant.

Although pregnancies typically come with some risks, risks of complications for the pregnant person and fetus are higher in those living with type 1 (T1DM) or type 2 diabetes (T2DM).

This article explores pregestational diabetes in more detail, including how it differs from gestational diabetes, risks, and treatment options.

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Pregestational diabetes is a form of diabetes mellitus that exists in a person before they become pregnant. Unlike gestational diabetes, which develops during pregnancy and typically resolves after childbirth, pregestational diabetes is a preexisting condition that requires ongoing management.

The primary types of diabetes that a healthcare professional can classify as pregestational diabetes are T1DM and T2DM.

T1DM is an autoimmune condition in which the body attacks the insulin-producing beta cells in the pancreas. T2DM occurs when the body cannot produce enough insulin to function correctly or the cells in the body do not react to insulin.

In 1949, doctor Priscilla White developed the White classification of pregestational diabetes. Doctors in the United States still sometimes use this to assess the risk of pregnancy complications. It classifies risk by looking at a person’s age, duration of diabetes, and the presence of diabetes complications.

However, it is important to note that the research to develop the classification system largely focused on people with T1DM rather than T2DM.

The classifications are as follows:

ClassAge of onset (years)Duration (years)Vascular disease
Bover 20under 10none
Dbefore 10over 20benign retinopathy
Ranyanyproliferative (increasing) retinopathy

Pregestational diabetes and gestational diabetes are two different conditions. The latter develops during pregnancy and typically resolves once the child has been born. The former is a preexisting condition that requires continuous management.

Diabetes typeTiming of onsetCausesManagement
gestationalduring pregnancyinsulin resistance and impaired glucose metabolism during pregnancydiet, exercise, and, in some cases, medication
T1DMbefore pregnancyautoimmune reaction destroying the insulin-producing cells within the pancreasinsulin, monitoring blood sugar, monitoring carbohydrates, exercise
T2DMbefore pregnancylifestyle factors and genesoral medication and, in some cases, insulin, diet, and exercise

Pregestational diabetes can increase the risk of complications for both the pregnant person and fetus. These can include:

By carefully planning diabetes management during pregnancy and working with healthcare professionals, a person with pregestational diabetes can reduce the risk of complications. Before pregnancy, a person may consider:

  • getting regular checkups and discussing pregnancy with a healthcare professional
  • having regular eye exams
  • managing blood glucose
  • quitting smoking, if applicable
  • stopping or changing certain prescription medications, such as cholesterol or hypertension drugs, under a doctor’s direction
  • taking prenatal vitamins
  • visiting an obstetrician or other specialist doctor

People with T1DM can manage their condition with insulin therapy, glucose monitoring, keeping their glucose level in their predetermined target range, and carbohydrate counting.

For those living with T2DM, treatment and management places emphasis on lifestyle changes such as diet and exercise. People living with T2DM may also require medication to help lower their glucose levels.

Most commonly, a doctor will prescribe metformin, but in some cases, they may recommend insulin as the most appropriate treatment option.

Other tips to help manage diabetes during pregnancy include:

  • attending all prenatal care checkups
  • following a healthcare professional’s guidance on managing blood sugar
  • taking insulin as directed by a healthcare professional
  • discussing other medications with a healthcare professional
  • discussing taking low dose aspirin with a healthcare professional, specifically whether it may help prevent preeclampsia
  • considering working with a dietician
  • discussing the likelihood of needing a cesarean section (C-section)

Managing pregestational diabetes before and during pregnancy is important for the well-being of both the pregnant person and the fetus. In the period before becoming pregnant, some steps a person can take to monitor their well-being include:

  • keeping blood glucose as close to their recommended target range as possible
  • getting regular checkups
  • following diabetes treatment plans
  • being physically active as advised by a healthcare professional
  • taking diabetes medicines exactly as prescribed, if applicable
  • stopping smoking, if applicable
  • taking vitamins if advised to do so by a healthcare professional

Pregestational or preexisting diabetes refers to when a person has diabetes before pregnancy. This differs from gestational diabetes as it occurs before pregnancy and does not resolve after pregnancy.

Pregestational diabetes requires ongoing management during pregnancy to reduce risks for both the pregnant person and fetus. Managing pregestational diabetes involves careful monitoring of blood sugar levels, a balanced dietary plan, regular physical activity, and, in some cases, medications.

With guidance from healthcare professionals, individuals with pregestational diabetes can have typical pregnancies and give birth to healthy babies.