The primary aim of this study is to determine if reducing exposure to dietary oxysterols with a plant-based, oxysterol-free diet that follows American Diabetes Association (ADA) guidelines (PB-ADAØ) will improve β-cell function and glycemic control among AAs with prediabetes and early diabetes (HbA1c 5.7% – 7.0%) when compared to the standard ADA (SADA) diet with oxysterols.