Diabetes mellitus in pregnancy

Last updated: August 16, 2023

Summarytoggle arrow icon

Diabetes in pregnancy refers to the presence of diabetes mellitus in a pregnant individual. Depending on whether the condition develops during pregnancy or was already present prior to the pregnancy, it is referred to as gestational diabetes and pregestational diabetes respectively.

Gestational diabetes mellitus is a condition of impaired glucose tolerance during pregnancy that most commonly develops during the second and third trimesters. Patients are usually asymptomatic but may develop polyhydramnios. The fetus is often large for gestational age. All pregnant women should be screened for gestational diabetes with an oral glucose challenge test. Diagnosis is confirmed with an oral glucose tolerance test (OGTT). Treatment involves glycemic control, e.g., dietary modifications and regular exercise. If glycemic control is insufficient, insulin therapy should be initiated. In most cases, gestational diabetes resolves after pregnancy, but complications may occur, including maternal type 2 diabetes mellitus, gestational hypertension, (pre)eclampsia, and diabetic fetopathy.

Pregestational diabetes refers to the presence of type 1 or type 2 diabetes mellitus prior to pregnancy. It is associated with a significantly increased risk for maternal and fetal complications during pregnancy and delivery. Management includes stringent glycemic control and close monitoring of fetal development (e.g., regular ultrasounds to screen for congenital abnormalities).

Gestational and pregestational diabetes mellitustoggle arrow icon

Overview of gestational and pregestational diabetes mellitus
Features Gestational diabetes mellitus [1][2] Pregestational diabetes mellitus [3]
Risk factors
Clinical features
Screening and diagnostics
  • Glycemic control
    • Dietary modifications and regular exercise (walking)
    • Strict blood glucose monitoring (4x daily)
    • Insulin therapy if glycemic control is insufficient with dietary modifications
    • Metformin and glyburide in patients who are unwilling or unable to use insulin
  • Regular ultrasound to evaluate fetal development
  • Consider inducing delivery at week 39–40, if glycemic control is poor or if complications occur
  • Stringent glycemic control (exercise, diet, insulin therapy)
  • Delivery and postpartum
    • Consider early delivery if the patient has poor glycemic control or preeclampsia
    • Consider C-section if estimated fetus weight > 4500 g
    • Intrapartum IV insulin and dextrose to avoid blood glucose fluctuations (maintain blood glucose level between 80–100 mg/dL; hourly blood glucose measurements

Fetal and neonatal complications of diabetes mellitus in pregnancytoggle arrow icon

Pregestational diabetes poses a greater risk of complications than gestational diabetes. Complications during the first trimester are more common in pregestational diabetes, while complications during the second and third trimesters are equally associated with pregestational and gestational diabetes. [4]

Diabetic embryopathy

Manifestations of diabetic embryopathy [4]

Diabetic fetopathy

Manifestations of diabetic fetopathy [4]

Referencestoggle arrow icon

  1. Kliegman RM, Stanton BF, Geme JS, Schor NF, Behrman RE. Nelson Textbook of pediatrics. Elsevier (2011) ; 2011
  2. Pillay J, Donovan L, Guitard S, et al. Screening for Gestational Diabetes. JAMA. 2021; 326 (6): p.539.doi: 10.1001/jama.2021.10404 . | Open in Read by QxMD
  3. Allen SR. Gestational Diabetes. Treat Endocrinol. 2003; 2 (5): p.357-365.doi: 10.2165/00024677-200302050-00007 . | Open in Read by QxMD
  4. ACOG Practice Bulletin No. 201. ACOG Practice Bulletin No. 201. Obstetrics & Gynecology. 2018; 132 (6): p.e228-e248.doi: 10.1097/aog.0000000000002960 . | Open in Read by QxMD

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