Project Summary Despite tremendous advances in diabetes, many Americans continue to have poor control over risk factors such as blood glucose, blood pressure, and cholesterol. As a result, diabetes continues to be a leading cause of death and many preventable complications, such as heart disease, stroke, chronic kidney disease, visual loss, and amputation. Many adults with diabetes still lack access to a coordinated healthcare team and do not complete evidence-based preventive services, receive medications or technologies that may improve disease care, participate in self-management behaviors, or follow-up for early detection and treatment of comorbidities and complications. This gap between evidence and practice disproportionately impacts the aged, those with disabilities, and the poor. As the primary health insurer for these vulnerable groups, Medicaid policies that expand eligibility requirements or lower barriers for initiating high value medications have the potential to improve healthcare engagement, delivery, and outcomes. States have a great deal of flexibility in administering Medicaid programs, and the Affordable Care Act and other health reforms further catalyzed state-level variation in eligibility, coverage, population management services, and financing. This variation presents a tremendous opportunity for natural experiments to evaluate the comparative effectiveness and costs of policy shifts on the care and outcomes of diabetes in vulnerable groups for whom the burden of diabetes is highest. We propose a Natural Experimental Research Center that will evaluate: 1) health and economic effects of state-specific variation in Medicaid managed care approaches for pharmacy utilization management affecting a newer class of diabetes medications with high costs but unique benefits: SGLT2 inhibitors; and 2) the medium- to longer-term effects of ACA expansion of health insurance coverage for adults with diabetes. We will leverage our access to two unique longitudinal datasets: (i) national claims data from UnitedHealth Group, a major Medicaid managed care provider for 6 million people in 27 states; and (ii) multi-state (Illinois, Indiana, Wisconsin) electronic heath records linked to Medicaid and Medicare claims. Outcomes of interest will include medication adherence, diabetes care quality, cardiometabolic risk factor control, acute diabetes complications, other forms of healthcare utilization, and costs. To evaluate state policies for medication utilization management, we will use difference-in-differences designs involving matched comparators in states with different policies. We will use the linked EHR-claims data from three states in novel, hybrid regression discontinuity (RD) and DiD designs to study the longer-term effects of ACA insurance expansion. Through direct engagement of collaborators and data contributors in participating states, our studies have been designed around high priority questions involving the effectiveness of parti...