Evidence Pack: Would the Bipartisan INSULIN Act of 2026 Actually Cap Costs for Everyone?

A renewed bipartisan effort in the United States Senate is attempting to close a massive gap in prescription drug affordability. Introduced in March 2026, the Improving Needed Safeguards for Users of Lifesaving Insulin Now (INSULIN) Act—designated as S. 4189—aims to cap out-of-pocket insulin costs at $35 per month for Americans enrolled in private and employer-sponsored health insurance. Championed by Senators Jeanne Shaheen (D-NH), Susan Collins (R-ME), Raphael Warnock (D-GA), and John Kennedy (R-LA), the legislation represents a rare point of cross-party consensus in an otherwise fractured political landscape.[1][4]

The central claim driving the legislation is that the majority of diabetics remain exposed to volatile and high out-of-pocket costs despite recent federal action. The evidence supporting this assertion is robust. While the Inflation Reduction Act of 2022 successfully capped insulin costs at $35 a month, that provision applied exclusively to Medicare beneficiaries.[3][7]

According to a 2026 white paper published by the actuarial firm Milliman, approximately 70 percent of individuals with Type 1 diabetes are not covered by the federal Medicare cap. This leaves millions of working-age Americans reliant on the commercial insurance market, where high deductibles and complex formulary tiers can expose them to the full list price of the life-saving biologic.[5]

Some states have attempted to fill this void. As of 2026, 26 states and the District of Columbia have implemented their own insulin copay caps for state-regulated health plans, ranging from $25 to $100 per month. However, the evidence shows this creates a fragmented safety net. Individuals covered by self-funded employer plans—regulated federally under the Employee Retirement Income Security Act (ERISA)—are exempt from these state-level caps, leaving a significant portion of the workforce unprotected.[5][7]

Another major argument from the bill's sponsors is that high out-of-pocket costs lead directly to dangerous medical rationing. The data robustly supports this claim. The Endocrine Society and the Centers for Disease Control and Prevention report that in 2021, nearly one in five American adults with diabetes—approximately 1.3 million people—rationed their insulin due to financial concerns.[2]

Rationing insulin can lead to diabetic ketoacidosis, a life-threatening condition that results in costly emergency room visits and long-term complications. By extending the $35 cap to the commercial market, lawmakers argue the federal government will actually reduce overall healthcare expenditures by preventing these acute medical crises.[4][8]

Critics and patient advocates often ask whether the INSULIN Act of 2026 will protect uninsured Americans, who are historically the most vulnerable to high list prices. The evidence here reveals a partial, rather than universal, solution. The legislation does not mandate a blanket $35 price cap for uninsured buyers at the pharmacy counter.[1][3]

Instead, S. 4189 establishes a pilot grant program across 10 states. This initiative would provide funding to community health centers and state agencies to identify uninsured diabetes patients and supply them with insulin at the $35 monthly rate. While this represents a lifeline for those in the pilot states, advocacy groups note that it falls short of the comprehensive federal protection offered to the insured population.[1][8]

Lawmakers also claim the bill targets the root causes of high list prices by heavily regulating Pharmacy Benefit Managers (PBMs). The legislative text confirms this structural mechanism. PBMs act as middlemen, negotiating rebates from drug manufacturers in exchange for placing their insulins on favorable insurance tiers.[2][6]

Under the INSULIN Act, PBMs would be mandated to pass 100 percent of these negotiated insulin rebates and discounts directly back to the health plan sponsors within 90 days. The evidence suggests this would eliminate the perverse incentives that encourage PBMs to favor insulins with higher list prices—and correspondingly higher rebates—over cheaper generic or biosimilar alternatives.[6][8]

Finally, some industry observers argue that pharmaceutical companies are already capping prices voluntarily, rendering federal legislation unnecessary. The evidence for this is mixed. Following public pressure, major manufacturers like Eli Lilly, Novo Nordisk, and Sanofi have indeed lowered list prices for several older insulins and introduced voluntary $35 savings programs for both commercially insured and uninsured patients.[3][7]

However, health policy experts consider these voluntary measures to be a weak long-term safeguard. Corporate discount programs require patients to navigate complex enrollment portals, are not legally binding, and can be altered or revoked by the manufacturers at any time. The INSULIN Act of 2026 seeks to codify these protections into federal law, ensuring that affordability is a guaranteed right rather than a corporate concession. The bill currently sits with the Senate Health, Education, Labor, and Pensions (HELP) Committee, awaiting a markup.[2][6]