A bill that just passed in the state Senate could be life-changing for the nearly 2 million Californians with chronic diseases.

Proposed by physician and Sen. Richard Pan, D-Sacramento, Senate Bill 568 would require state-regulated, high-deductible health plans to provide “first-dollar coverage” for preventive chronic disease medications and diabetes supplies.

Currently, patients must pay out of pocket for these drugs, up until they reach an annual deductible limit. Under the proposed law — now being considered by the Assembly — insurers could not charge a deductible for the medications.

This change would have an enormous impact for patients who need consistent medication to manage long-term conditions like heart disease, high blood pressure and diabetes. Not only could the bill save them thousands of dollars a year while improving their health — it could also save millions of dollars for the health care system by improving adherence.

Failing to take medications as prescribed, known as “nonadherence,” has serious consequences. Nearly a third of people who deviated from their doctors’ orders ended up seeing their conditions get worse rather than better, according to a Kaiser Family Foundation poll. One study found that as many as 125,000 Americans die every year due to nonadherence.

The problem is magnified for people with chronic disease who are facing health care decisions day in and day out. More than 60% of Americans have at least one chronic illness, and 42% have two or more. For these patients, requiring large deductibles be met before covering medication costs can be especially harrowing.

Consider two patients whose plans require $2,000 in personal spending before the insurance company picks up the tab.

One is a healthy young person who spends a hundred dollars a year on medication — perhaps on antibiotics to treat short-lived infection or injury. She may have to cover the medications out-of-pocket, but with purchases spread throughout the year, the cost is manageable.

A chronic disease patient, on the other hand, can easily spend $1,000 in January alone, and still be only halfway to the deductible limit. That significant financial burden could lead him to ration his prescriptions or leave the medicine at the pharmacy altogether.

Half of people with chronic conditions report nonadherence, with many citing high costs as a driving cause. A quarter of patients with diabetes have rationed insulin, which they need to stay alive.

When patients are unable to take medications as instructed, they can end up requiring additional treatment, costing themselves and the health care system. Nationwide, problems caused by nonadherence account for 10 percent of hospital visits and cost nearly $300 billion in a typical year.

The drug adherence crisis cannot be solved by one state law alone, but Pan’s bill is a step in the right direction and could set a national example.

We know that his proposed rule change is feasible because it would build on protections that already exist for other medical coverage. Under the Affordable Care Act, insurance companies must provide first-dollar coverage for preventive care, covering blood pressure screenings and routine vaccinations before patients have met their deductibles.

The important reality is that, in the long run, insurers could save money through improved adherence and better health outcomes for patients as a result.

Out-of-pocket cost is a major barrier to medical care. Requiring first-dollar coverage for preventive chronic disease treatments can make strides toward making health care affordable.

Kenneth E. Thorpe is a professor of health policy at Emory University and chairman of the Partnership to Fight Chronic Disease.