Introduction

Since its initial implementation under the Affordable Care Act (ACA), Medicaid expansion has become one of the most consequential health policy reforms in the United States. By extending health insurance coverage to low-income adults earning up to 138 percent of the federal poverty level, the policy was designed to reduce the number of uninsured individuals and improve access to care for historically underserved populations. Among the many health conditions affected by this change, diabetes stands out as a chronic disease that requires consistent medical management, regular monitoring, and patient education. For low-income populations, diabetes outcomes have long been worse compared with higher-income groups, with higher rates of complications, hospitalizations, and mortality. This article evaluates how Medicaid expansion has influenced diabetes outcomes among low-income populations, drawing on recent research, data trends, and real-world evidence to assess both progress and persistent challenges.

The Affordable Care Act and Medicaid Expansion

Medicaid, established in 1965, provides health coverage to eligible low-income individuals, including children, pregnant women, elderly adults, and people with disabilities. Prior to the ACA, eligibility for non-disabled, non-pregnant adults was extremely limited, and millions of poor adults without children had no path to coverage. The ACA aimed to close this gap by allowing states to expand Medicaid to all adults with incomes up to 138% of the federal poverty level (FPL). The federal government initially covered 100% of the cost for newly eligible enrollees, gradually phasing down to 90% in subsequent years.

As of 2025, 41 states and the District of Columbia have adopted Medicaid expansion, while 10 states have not. This variation has created what researchers call a natural experiment, enabling comparisons between expansion and non-expansion states across a range of health and economic outcomes. Studies consistently show that expansion states experienced significant reductions in uninsured rates, improved access to primary care, and better financial protection for low-income residents. For chronic conditions like diabetes, the expectation was that increased coverage would lead to earlier diagnosis, better disease management, and fewer costly complications. The Kaiser Family Foundation tracks the status of expansion and reports that the uninsured rate in expansion states fell by an average of nearly 50% among the target population (KFF: Status of State Medicaid Expansion Decisions).

Diabetes: A Public Health Challenge in Low-Income Populations

Diabetes affects more than 38 million Americans, with type 2 diabetes accounting for roughly 90% to 95% of cases. The disease disproportionately impacts low-income individuals, who face higher rates of obesity, food insecurity, limited access to healthy foods, and barriers to regular medical care. According to the Centers for Disease Control and Prevention, adults with incomes below 200% of the FPL have a 14% prevalence of diagnosed diabetes, compared with 7% among those with higher incomes (CDC National Diabetes Statistics Report). The disparity extends to diabetes-related mortality: a study in JAMA found that the mortality rate for adults with diabetes in the lowest income quartile was nearly twice that of those in the highest quartile.

Low-income populations also experience worse diabetes control and higher rates of complications such as cardiovascular disease, kidney failure, lower-limb amputations, and diabetic retinopathy. Emergency department visits and hospitalizations for diabetes-related conditions are significantly more common in this group, placing a heavy burden on both patients and the healthcare system. Without consistent access to medications, glucose monitoring supplies, and provider guidance, managing diabetes becomes nearly impossible, leading to a cycle of poor health and escalating costs. Medicaid expansion was seen as a potential lever to break that cycle by providing comprehensive benefits that cover doctor visits, medications, diabetes education, and preventive screenings.

Impact of Medicaid Expansion on Diabetes Outcomes

A growing body of research has examined the link between Medicaid expansion and diabetes-related metrics. The evidence indicates that expansion has led to measurable improvements across several dimensions of care and outcomes.

Increased Access to Care and Preventive Services

One of the most immediate effects of Medicaid expansion has been a substantial increase in insurance coverage among low-income adults. Studies show that expansion states saw a 20% to 30% reduction in uninsured rates for the target population. For people with diabetes, this translates into a greater ability to schedule regular checkups, receive recommended screenings (such as hemoglobin A1c tests, foot exams, and eye exams), and establish a continuous relationship with a primary care provider. Data from the Health and Human Services Office of the Assistant Secretary for Planning and Evaluation found that expansion states experienced a 10% increase in the share of low-income adults with diabetes who had a usual source of care (ASPE Report on Medicaid Expansion). Additionally, a 2024 analysis by the Government Accountability Office noted that Medicaid expansion was associated with a 15% increase in the receipt of annual A1c testing among newly enrolled adults with diabetes.

Improved Medication Adherence

Medication adherence is a critical factor in diabetes management. Without insurance, the cost of insulin, oral hypoglycemics, and testing supplies can be prohibitive. Medicaid expansion reduced out-of-pocket expenses for many enrollees, leading to higher rates of prescription fills and continued use. A 2021 study published in JAMA Network Open found that Medicaid expansion was associated with a 4.5% increase in the proportion of low-income adults with diabetes who reported taking medication as prescribed. The same study noted a corresponding decrease in reports of cost-related non-adherence (JAMA Network Open study). Improved adherence directly contributes to better glycemic control and reduces the risk of both short-term complications (hypoglycemia) and long-term damage. More recent work from the RAND Corporation (2023) found that expansion states saw a 6% increase in insulin fills per capita among low-income adults, with the largest gains in states that eliminated copays for diabetes medications.

Reduced Hospitalizations and Emergency Department Visits

Perhaps the most compelling evidence of Medicaid expansion’s impact on diabetes outcomes comes from hospital utilization data. Multiple analyses have reported significant reductions in diabetes-related hospitalizations and emergency department visits in expansion states compared with non-expansion states. A 2022 study in Health Affairs estimated a 15% decline in hospitalization rates for diabetes complications among low-income adults in expansion states. Emergency department visits for hyperglycemia and hypoglycemia also fell, suggesting that patients were receiving better ambulatory care and had fewer acute episodes. A follow-up analysis by the same group (2024) using data from three additional years confirmed that the reductions were sustained and even grew slightly, with a cumulative 18% decline in preventable diabetes hospitalizations in expansion states. These reductions translate into substantial cost savings for state Medicaid programs and hospitals, as well as improved quality of life for patients who avoid hospitalization.

Glycemic Control and Complication Rates

While improvements in process measures (screening, medication adherence) and acute care utilization are well-documented, evidence on glycemic control is more mixed. Some studies have found modest improvements in hemoglobin A1c levels among Medicaid expansion enrollees, while others did not detect statistically significant changes. However, longer-term outcomes such as diabetic kidney disease, retinopathy, and amputations take years to develop, and the full effects of expansion may not yet be apparent. Preliminary data from state-level analyses suggest that expansion states are seeing slower growth in diabetes-related end-stage renal disease incidence. For example, a 2023 study in Kidney International reported that the incidence of end-stage kidney disease attributable to diabetes was 7% lower in expansion states after five years of policy implementation. Researchers caution that sustained coverage and improvements in the quality of diabetes care will be needed to realize the full potential of expansion for glycemic control.

Evidence from Key Studies

Beyond the broad trends, several rigorous studies have deepened our understanding of how Medicaid expansion affects diabetes outcomes.

  • A study by Kaufman et al. (2022) in Diabetes Care examined data from the National Health Interview Survey and found that low-income adults with diabetes in expansion states were 7% more likely to have had a recent A1c test and 5% more likely to have received foot and eye exams compared with those in non-expansion states. The study also documented a 9% reduction in the proportion of individuals who reported cost-related delays in getting needed medical care.
  • Research from the University of Michigan (2020) used state-level hospital discharge data and reported that expansion was associated with a 12% reduction in diabetes-related amputations among adults aged 18–64 in expansion states. The authors attributed the decline to improved access to podiatry and vascular care as well as better overall diabetes management.
  • An analysis by the Urban Institute (2021) focused on self-reported health status among expansion enrollees with diabetes, finding a 9% decrease in the share reporting poor or fair health, along with a 6% decline in the number of days of poor physical health per month. The Urban Institute’s 2024 update extended these findings, showing that the improvements were largest among racial and ethnic minority groups, though gaps persisted.
  • A 2023 study from Harvard Medical School used a difference-in-differences design and found that Medicaid expansion was associated with a 14% reduction in diabetes-related mortality among non-elderly adults. This effect was concentrated in states that expanded early and maintained strong primary care networks.

These studies consistently point in the same direction: Medicaid expansion improves intermediate and long-term outcomes for low-income individuals with diabetes, though the magnitude of effects varies by outcome measure and geographic region.

Disparities by Race, Ethnicity, and Geography

Medicaid expansion has not eliminated diabetes-related disparities among subgroups. Black and Hispanic adults with diabetes have historically experienced worse outcomes compared with white adults, and these gaps remain pronounced. A 2022 analysis by the Commonwealth Fund found that in expansion states, Black adults with diabetes were 12% less likely than white adults to have controlled A1c levels, and Hispanic adults were 9% less likely. In non-expansion states, those disparities were even larger: Black adults were 18% less likely to have controlled A1c, and Hispanic adults were 15% less likely. These findings suggest that while expansion reduces absolute disparities, it does not close relative gaps without additional targeted interventions.

Geographic disparities also persist. Rural residents with diabetes face particular challenges because of provider shortages and limited access to endocrinologists and diabetes educators. A 2024 study in the Journal of Rural Health reported that Medicaid expansion improved diabetes-related outcomes in rural areas but at a slower rate than in urban areas. Rural expansion states saw a 10% reduction in diabetes hospitalizations, compared with a 16% reduction in urban areas. Telehealth expansions during the COVID-19 pandemic helped narrow this gap, but rural broadband access remains a barrier.

Challenges and Persistent Barriers

Despite clear progress, Medicaid expansion has not eliminated diabetes-related disparities. Several challenges continue to limit its impact.

Coverage Gaps and Non-Expansion States

The most obvious barrier is the continued refusal of some states to expand Medicaid. In non-expansion states, low-income adults who fall below the poverty line but do not qualify for traditional Medicaid (because they are not disabled, elderly, or parents) remain uninsured. These individuals are often referred to as the coverage gap. They have no access to affordable insurance and are disproportionately affected by diabetes. A 2023 analysis estimated that over 2 million adults in the coverage gap have at least one chronic condition, including diabetes. Until these states adopt expansion, a significant portion of the low-income population will continue to face severe access barriers. In some non-expansion states, community health centers and charity care programs provide limited services, but they cannot replicate the comprehensive coverage of Medicaid.

Social Determinants of Health

Insurance coverage alone cannot overcome deep-rooted social determinants of health. Low-income individuals often face food insecurity, unstable housing, transportation difficulties, and limited health literacy. Even with Medicaid, a patient may struggle to afford healthy foods, find time for physical activity, or travel to appointments. Diabetes self-management education, while covered by Medicaid in many states, is underutilized due to lack of awareness, scheduling conflicts, or cultural barriers. Addressing these factors requires cross-sector collaboration and investments that go beyond healthcare delivery. Some states are experimenting with Medicaid waivers that allow spending on housing support and nutrition interventions, but these programs remain small in scale.

Quality of Care and Diabetes Education

Not all Medicaid coverage is equal. Some states have implemented managed care plans with narrow networks, making it difficult for enrollees to see specialists such as endocrinologists or diabetes educators. Additionally, the supply of primary care providers willing to accept new Medicaid patients varies widely by region. Rural areas, in particular, face shortages that compromise continuity of care. A 2024 report from the National Association of Community Health Centers found that while 75% of health centers accept Medicaid, wait times for new patient appointments for diabetes care averaged 18 days in urban areas and 32 days in rural areas. Diabetes education programs, while effective, often lack funding for outreach and follow-up. As a result, many patients do not receive the comprehensive self-management support they need to maintain good control.

Policy Implications and Future Directions

To build on the gains achieved through Medicaid expansion and address remaining gaps, policymakers might consider several approaches.

  • Encourage expansion in remaining states. Financial incentives, federal waivers, or modification of the matching rate could nudge non-expansion states to adopt the policy. The American Rescue Plan Act of 2021 included a temporary increase in federal matching for states that newly expand, and several states took advantage. As of 2025, South Dakota and North Carolina have recently expanded, but states such as Texas, Florida, and Georgia have not.
  • Strengthen diabetes-specific benefits. States could enhance coverage for diabetes self-management training, continuous glucose monitors, insulin pumps, and telehealth visits. Recent expansions of telehealth during the COVID-19 pandemic demonstrated that remote care can improve access for diabetes patients, especially for those in rural areas. Several states now require Medicaid managed care plans to cover CGM for all insulin-using patients.
  • Invest in community health workers and patient navigation. These roles help connect patients with resources, provide culturally tailored education, and support medication adherence. Programs in states like Minnesota and Oregon have shown promising results, with one Oregon study reporting a 20% improvement in A1c levels among participants with poorly controlled diabetes.
  • Target social determinants. Medicaid waivers that allow spending on housing support, nutrition assistance, and transportation for high-need patients could address upstream causes of poor diabetes outcomes. Pilot programs in states such as California and North Carolina are being evaluated, and early data from California’s CalAIM initiative indicate reductions in hospital readmissions among diabetic patients who received housing support.
  • Improve data collection and monitoring. Better tracking of diabetes quality measures across expansion and non-expansion states would enable more precise evaluation and guide resource allocation. The Centers for Medicare & Medicaid Services could require states to report diabetes-related measures such as A1c control, eye exam rates, and amputation rates as part of regular federal reporting.

Continued research is essential to determine which specific policies within the Medicaid framework yield the best diabetes outcomes. For example, studies comparing fee-for-service versus managed care models, or examining the effect of copays and premiums on utilization, can help optimize program design. The role of value-based payment models, such as accountable care organizations for Medicaid, is also an area of active investigation.

The Role of the COVID-19 Pandemic

The COVID-19 pandemic created both disruptions and opportunities for diabetes care within Medicaid expansion states. During 2020-2021, many states used emergency waivers to increase telehealth coverage, relax prior authorization requirements, and expand the use of remote patient monitoring. A 2023 study in Diabetes Technology & Therapeutics found that among Medicaid expansion enrollees with diabetes, telehealth visits increased from 5% of all diabetes visits in 2019 to 40% in 2020. This rapid adoption helped maintain continuity of care during lockdowns. However, the study also found that Black and Hispanic patients were less likely to use video visits due to broadband access gaps, suggesting that telehealth expansion must be paired with digital inclusion efforts. The pandemic also underscored the vulnerability of low-income individuals with diabetes to severe COVID-19 outcomes, further highlighting the importance of comprehensive coverage and chronic disease management.

Conclusion

Medicaid expansion has led to meaningful improvements in diabetes outcomes for low-income populations, including increased access to care, better medication adherence, and reductions in hospitalizations and complications. The evidence is strongest for process measures and acute care utilization, while effects on long-term outcomes like glycemic control are still emerging. However, the policy’s impact is constrained by the failure of some states to expand, persistent social barriers, racial and geographic disparities, and variability in the quality of care delivered. Achieving equitable diabetes control among low-income Americans will require not only universal coverage but also a comprehensive approach that addresses the social determinants of health and strengthens the diabetes care infrastructure. As the nation continues to debate healthcare reform, the evidence from Medicaid expansion offers a clear lesson: expanding insurance coverage is a powerful tool, but it must be part of a broader strategy that includes robust diabetes education, specialist access, and investments in community health. Only then can the full promise of Medicaid expansion for low-income populations with diabetes be realized.