Screening for Gestational Diabetes Mellitus

Risk Factors for Gestational Diabetes

Women with a body mass index (BMI) ≥30 kg/m² are at high risk for gestational diabetes, as are those with a previous history of gestational diabetes (4.14 times higher risk), family history of diabetes in first-degree relatives, previous delivery of a macrosomic infant (>4.05 kg or 9 lb), marked obesity, glycosuria, high-risk ethnicity (Hispanic, Native American, South/East Asian, African American, Pacific Islander), and history of polycystic ovary syndrome 1, 2, 3, 4
The American College of Obstetricians and Gynecologists recommends that women with these risk factors undergo formal glucose testing as soon as feasible at their first prenatal visit 1, 2, 3

Fasting plasma glucose ≥126 mg/dL (7.0 mmol/L) confirms diabetes if repeated on subsequent day, and random plasma glucose ≥200 mg/dL (11.1 mmol/L) with symptoms also confirms diabetes 3, 5
The American Diabetes Association recommends using venous plasma glucose measurements, not point-of-care capillary glucose, for diagnostic purposes 1, 2, 3

High-risk women should undergo formal diagnostic testing immediately using either a one-step approach (75g OGTT) or a two-step approach (50g glucose challenge test followed by 100g OGTT if positive) 4, 5, 6
Average-risk women should undergo standard screening at 24-28 weeks gestation, while low-risk women may not require screening if they meet certain criteria (age <25 years, normal pre-pregnancy weight, no family history of diabetes, not from high-risk ethnic group) 1, 2, 3, 4

Women diagnosed with gestational diabetes require 75g OGTT at 4-12 weeks postpartum to assess for persistent diabetes, followed by lifelong screening every 2-3 years 4, 5, 6