GRADE (Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study) is a 36-center unmasked, parallel treatment group, randomized controlled trial evaluating four diabetes medications added to metformin in people with type 2 diabetes (T2DM). We report baseline characteristics and compare GRADE participants to a National Health and Nutrition Examination Survey (NHANES) cohort. Participants were age ≥30 years at the time of diagnosis, with duration of T2DM <10 years, HbA1c 6.8-8.5% (51-69 mmol/mol), prescribed metformin monotherapy, and randomized to glimepiride, sitagliptin, liraglutide, or insulin glargine. At baseline, GRADE's 5,047 randomized participants were 57.2 ± 10.0 years of age, 63.6% male, with racial/ethnic breakdown of 65.7% white, 19.8% African American, 3.6% Asian, 2.7% Native American, 7.6% other or unknown, and 18.4% Hispanic/Latino. Duration of diabetes was 4.2 ± 2.8 years, with mean HbA1c of 7.5 ± 0.5% (58 ± 5.3 mmol/mol), BMI of 34.3 ± 6.8 kg/m2, and metformin dose of 1,944 ± 204 mg/day. Among the cohort, 67% reported a history of hypertension, 72% a history of hyperlipidemia, and 6.5% a history of heart attack or stroke. Applying GRADE inclusion criteria to NHANES indicates enrollment of a representative cohort with T2DM on metformin monotherapy (NHANES cohort average age, 57.9 years; mean HbA1c, 7.4% [57 mmol/mol]; BMI, 33.2 kg/m2; duration, 4.2 ± 2.5 years; and 7.2% with a history of cardiovascular disease). The GRADE cohort represents patients with T2DM treated with metformin requiring a second diabetes medication. GRADE will inform decisions about the clinical effectiveness of the addition of four classes of diabetes medications to metformin. © 2019 by the American Diabetes Association.