The Effect of Medicaid Expansion on Care for Patients With Diabetes by Primary Care Provider Supply

We examined whether Medicaid expansion led to improvements in health, access, and preventive care for low-income adults with diabetes, varying by primary care provider (PCP) supply. Using 2011-2021 Behavioral Risk Factor Surveillance System data and a difference-in-differences approach, we compared outcomes before and after expansion in states classified by PCP supply. The sample included 85,375 adults aged 18-64 with incomes below 138% of the federal poverty level and a diabetes diagnosis. Outcomes were self-reported: health insurance coverage, personal doctor, cost-related delays in care, routine checkups, flu shots, and days with poor mental or physical health. Across all states, Medicaid expansion was associated with a 3.2 and 3.5 percentage-point (pp) increase in insurance coverage and checkup visits, respectively. High-PCP-supply states realized larger gains in coverage (6.4 pp) as well as improvements in routine checkups (3.3 pp) and flu vaccination (3.5 pp). They also showed a reduction of nearly one day of poor mental health per month. In contrast, low-PCP-supply states experienced a marginally significant increase in poor mental health days. Medicaid expansion improved coverage, preventive care, and mental health outcomes for low-income adults with diabetes, with more pronounced benefits in high-PCP-supply states. These findings underscore the importance of adequate PCP capacity to optimize the impact of coverage expansions in managing chronic conditions such as diabetes. Policymakers aiming to enhance care for vulnerable patients with diabetes should consider investing in primary care infrastructure alongside coverage expansions.