A new study examining insulin access patterns over 13 years reveals troubling disparities that persist despite recent cost stabilization efforts, with lower-income patients consistently filling fewer insulin prescriptions than their higher-income counterparts. The research, published in The American Journal of Managed Care, analyzed claims data from privately insured individuals across all 50 states from 2008 to 2021.
Cost Trends and Usage Patterns
The study documented a steep rise in insulin out-of-pocket costs between 2008 and 2014, followed by stabilization and a minimal decline by 2021. During the cost increase period, researchers observed a corresponding decline in prescription fills, while cost stabilization coincided with increased fill rates.
"We saw that during the period of time in which the costs were rising, there was a slight decline in the number of fills by the end of that period. Then, when the cost stabilized out, and even decreased, we noticed an increase in the number of fills per year," explained lead investigator Elise S. Tremblay, MD, MPH, a pediatric endocrinologist at Boston Children's Hospital and Boston Medical Center.
The cost fluctuations were attributed to several factors, including the transition from older, generic insulin formulations to newer, patented analog insulins. "Many years ago, we used less sophisticated insulin analogs that eventually became generic and were relatively inexpensive for patients. Over the last 10 to 20 years or so, there's been a rise in different subtypes of insulin analogs that are, because they're newer, patented cost more money," Tremblay noted.
Persistent Income-Based Disparities
The most striking finding was the consistent gap in insulin access between income groups. Using zip code-level poverty data from the American Community Survey, researchers found that higher-income individuals consistently filled more 30-day supplies of insulin per year compared to lower-income patients throughout the entire study period.
"For me, the most significant and somewhat surprising finding was how consistent the disparity was between higher-income and lower-income individuals. Although both of their rates over time in terms of the number of 30-day fills per year did vary over the study period, the gap between the 2 of them was highly consistent," Tremblay observed.
Health System Impact
The study methodology involved analyzing annualized prescription fills, examining how many 30-day supplies patients obtained per year. Since a full year requires 12 monthly supplies, patients filling only nine supplies would be without medication for approximately 25% of the year, creating significant health risks.
The health implications of reduced insulin access are severe and multifaceted. "Without insulin, individuals with diabetes' blood sugar rises to an unhealthy level, which affects all the vital organs of the body, the heart and the kidneys in particular," Tremblay explained.
Short-term complications include emergency department visits for hyperglycemic emergencies such as diabetic ketoacidosis or hyperglycemic hyperosmolar state, often requiring intensive care and prolonged hospitalizations. Long-term consequences encompass heart disease, kidney disease, and other organ damage from chronically elevated blood sugar levels.
High-Deductible Plan Effects
The research specifically examined the impact of high-deductible health plans with savings options, which require patients to pay higher out-of-pocket costs before insurance coverage begins. These plan structures showed more pronounced cost increases during the peak period, particularly affecting insulin accessibility.
"When you have a high-deductible health plan, that means that individuals are responsible for a higher proportion of their health plan costs, but they typically pay a lower premium. Then, a high-deductible health plan with a savings option suggests that individuals are paying even more out of pocket," Tremblay noted.
Policy Interventions and Future Outlook
Recent efforts to address insulin affordability include the implementation of preventative drug lists by health insurance providers, where essential medications receive higher coverage rates. Legislative initiatives have also emerged, with Congress implementing caps on monthly insulin costs for individuals requiring this life-sustaining medication.
Despite these interventions, the persistent disparities highlighted in the study underscore the ongoing challenges in ensuring equitable access to essential diabetes medications. The research demonstrates that even as overall costs stabilize, structural inequalities in healthcare access continue to affect the most vulnerable patient populations.
"By not allowing individuals access to the medications that they need to control their disease, we guarantee that they will have short- and long-term complications that will worsen their morbidity and mortality over time, as well as add extra cost to the health care system," Tremblay concluded.
