Gestational diabetes mellitus

Updated: 01/21/2021

General features

Glucose intolerance of variable degree with onset or first recognition during pregnancy
Higher risk for stillbirth, congenital malformations, macrosomia, obesity and diabetes later in life
Resolved following delivery, but may develop into diabetes afterward
Proper managements reduce risk of preeclampsia, macrosomia and shoulder dystocia

Risk factors

History of impaired glucose tolerance, HbA1C ≥5.7
Hispanic American, African American, Native American, South or East Asian, Pacific Islander
Family history of diabetes
Overweight Older age (>30)
History of unexplained perinatal loss or malformed infant, macrosomia
Glycosuria
High density lipoprotein < 35 mg/dl, triglyceride > 250 mg/dl
Multiple gestation

Key pathogenesis

Insulin resistance associated with pregnancy
Placental secretion of diabetogenic hormones including growth hormone, corticotropin-releasing hormone, placental lactogen, prolactin, and progesterone

Screening guidelines per American Diabetes Association

Average-risk patients: 24-28 weeks of gestation
High-risk patients: As early as feasible, and repeat at 24-28 weeks, if first screening test is negative
High-risk factors:

Obesity

Strong family history of type 2 DM

Personal history of GDM

Glucose intolerant

Glucosuria

Diagnosis

Identify asymptomatic individuals with high risk

50-gram one hour glucose screen, positive if plasma glucose level ≥140 mg/dL at 1 hour

Performed if screening test positive

100-gram oral glucose tolerance test, positive if at least two results below present

≥95 mg/dL, ≥180 mg/dL, ≥155 mg/dL and ≥140 mg/dL at fasting status, one, two and three hours after 100-gram oral glucose load, respectively

Pathology Notes