This quasi-experimental study evaluated racial/ethnic disparities in health insurance and differences in visits post-versus pre-Affordable Care Act (ACA) Medicaid expansion. We utilized electronic health record data from a population of patients with diabetes aged 19-64 seen in community health centers (CHCs). We used generalized estimating equation Poisson models to estimate incidence rates of insurance type and visits post-(1/1/2014-12/31/2015) versus pre-(1/1/13-12/31/13) ACA, stratified by racial/ethnic group. We assessed difference-in-differences (DD) and difference-in-difference-in-differences (DDD). The relative disparity in uninsured visits increased between Hispanic and non-Hispanic Whites in expansion states (DD=1.93; 95% CI=1.41, 2.64); the magnitude was greater in expansion compared with non-expansion states (DDD=1.84, 95% CI=1.32, 2.56), yet uninsured rates were lower in expansion compared with non-expansion states. We found few changes in visits. Results suggest that the ACA Medicaid expansion increased health insurance coverage and that while some racial/ethnic disparities were improved, some remained.