Context: Previous research has suggested that activation of the renin-angiotensin-aldosterone system may promote insulin resistance and β-cell dysfunction but the association with incident diabetes in African Americans is unknown. Objective: We examined the association between, both aldosterone and renin, and insulin resistance, β-cell function, and incident diabetes in a large African American cohort. Design: The Jackson Heart Study is a prospective study of the development and progression of cardiovascular disease in African Americans. Setting: Participants were recruited from the tri-county area of metropolitan Jackson, MS. Participants: 5,301 African American adults, aged 21–94 years, were assessed at baseline and through 12 years of follow-up. Data on aldosterone, renin and risk factors was collected at baseline (2000–2004). Diabetes (fasting glucose ≥126 mg/dL, physician diagnosis, use of diabetes drugs, or HbA1c ≥ 6.5%) was assessed at baseline and through 12 years of follow-up. Participants were excluded for missing data on baseline covariates or diabetes follow-up. Cox regression was used to estimate hazard ratios (HR) for incident diabetes using sequential modeling adjusting for age, sex, education, occupation, systolic blood pressure, current smoking, physical activity, dietary intake and BMI. Exposures: Aldosterone, renin, and diabetes risk factors Outcomes: Homeostatic model assessment – insulin resistance (HOMA-IR) and incident diabetes Results: Among 3,234 participants over a median of 8.0 years of follow-up there were 554 cases of incident diabetes. Every 1% increase in log-tranformed aldosterone was associated with a 0.18% higher log-transformed HOMA-IR in cross-sectional analyses of non-diabetic participants (p<0.001). Log- transformed aldosterone and renin levels in the fifth vs. First quintile were associated with a 78% (HR 1.78, 95%CI: 1.35, 2.34) and 35% (HR 1.35, 95%CI: 1.06, 1.72) increase in diabetes risk, respectively, in fully-adjusted models. Conclusions: Activation of the renin-angiotensin-aldosterone system may play a significant role in the development of insulin resistance and diabetes in African Americans.