OBJECTIVE We assessed the relation of diabetes and insulin resistance (IR) on left ventricular (LV) structure and function in African Americans. RESEARCH DESIGN AND METHODS Among those receiving echocardiograms in cycle 1 of the Jackson Heart Study, we assessed the sex-specific relation of fasting blood glucose (FBG), diabetes, and IR to LV structure and function, adjusting for age, systolic blood pressure, antihypertensive medications, and BMI. RESULTS Among 2,399 participants, LV mass index (Pwomen = 0.0002 and Pmen = 0.02), posterior wall thickness (Pwomen = 0.01 and Pmen = 0.05), and interventricular septal wall thickness (Pwomen = 0.01) were related to FBG categories. Among those with normal FBG and no diabetes, concentric remodeling and low ejection fraction in women and LV mass index and posterior wall thickness in men were related to IR. CONCLUSIONS In the largest study of its kind in a community-based cohort of African Americans, we found a relation of FBG category and IR to LV structure and function.