Risk factors include the following: Previous gestational diabetes A macrosomic infant in a previous pregnancy Unexplained fetal losses Prepregnancy body mass index (BMI) > 30 kg / m2 Maternal age > 40 years Family history of diabetes Some races or ethnicities associated with higher rates of diabetes (eg, people with Hispanic-American, African-American, American Indian, Asian, or Pacific Islander ancestry) Screening and confirmation of the diagnosis of gestational diabetes can be done in 1 or 2 steps: 1-step test: A fasting, 75-g glucose, 2-hour oral glucose tolerance test (GTT) 2-step test: A non-fasting, 50-g glucose, 1-hour GTT; if abnormal (≥ 135 mg / dL/7.5 mmol / L), then a fasting, 100-g, 3-hour GTT The diagnosis is best based on results of an oral glucose tolerance test (OGTT—see table Glucose Thresholds for Gestational Diabetes Mellitus Using a 3-hour Oral Glucose Tolerance Test).