Gestational diabetes mellitus

Last updated: January 13, 2022

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Gestational diabetes mellitus is a condition of impaired glucose tolerance during pregnancy that mostly occurs in the second and third trimesters. Patients are usually asymptomatic but may present with 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 includes glycemic control, e.g., dietary modifications and regular exercise. If glycemic control is insufficient, insulin therapy is initiated. In most cases, gestational diabetes resolves after pregnancy. However, complications may occur, including gestational hypertension, (pre)eclampsia, and development of type 2 diabetes mellitus in the mother and diabetic fetopathy and shoulder dystocia in the fetus.

Pregestational diabetes is type 1 or type 2 diabetes mellitus that is already present prior to pregnancy, and 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).

Features Gestational diabetes mellitus [1] Pregestational diabetes mellitus [2]
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
  • In most cases, gestational diabetes resolves after pregnancy.
  • Increased risk of gestational diabetes recurring in subsequent pregnancies (∼ 50%)
  • Increased risk of developing T2DM (up to 50% over 10 years) → screen for DM 6–12 weeks postpartum (75 g 2-hour GTT); repeat every 3 years
  1. Chiefari E, Arcidiacono B, Foti D, Brunetti A. Gestational diabetes mellitus: an updated overview. J Endocrinol Invest. 2017; 40 (9): p.899-909. doi: 10.1007/s40618-016-0607-5 . | Open in Read by QxMD
  2. 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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