UnitedHealthcare, the nation’s largest health insurance company, is incorporating the world’s top-selling wristwatch into wellness plans for millions of beneficiaries.

Minnetonka-based UnitedHealth Group, which owns UnitedHealthcare, said Wednesday that it has made changes to its internal systems so that the Apple Watch can be used to track steps and get credit toward personal goals in a wellness plan called UnitedHealthcare Motion.

Previously, the Motion plan only accepted data from smartwatches and wearables from brands including FitBit, Samsung and Garmin. Adding the Apple Watch is intended to expand the reach of the program. Apple CEO Tim Cook said last year that the device had become the world’s top-selling wristwatch.

“Suffice it to say, it is an extremely attractive and impactful product,” Paul Sterling, vice president of emerging products at UnitedHealthcare, said Wednesday. “We’re very excited about adding Apple Watch to UnitedHealthcare Motion.”

UnitedHealthcare Motion is a program that employers can make available to beneficiaries in their group coverage to create financial incentives to improve fitness through walking.

Beneficiaries in the wellness plan can earn up to $4 per day for meeting three goals, depending on plan details. Those dollars can be applied toward the purchase of the Apple Watch.

UnitedHealthcare is offering beneficiaries the ability to get an Apple Watch for roughly the cost of shipping and taxes, and then pay down the balance of the device cost with their daily fitness rewards, in what it calls the Walk It Off program.

Once the device is paid off, probably after around six months, the rewards will flow into the beneficiaries’ tax-advantaged health spending accounts.

First launched on a limited basis in 2016, the Motion wellness plan option is becoming available for all employer-sponsored plans offered by UnitedHealthcare, including smaller and midsize employers and large self-insured plans administered by the Minnesota company. The wellness option is not available for nongroup plans, and it may not be available in some areas because of state laws.

Participants in the program are averaging nearly 12,000 steps per day, more than double the U.S. average. And although wearable motion trackers have been criticized for mobilizing people who are already fit, the UnitedHealthcare Motion plan appears to be engaging people beyond traditional fitness buffs.

Patients dealing with chronic health conditions are 20 percent more likely than those without those problems to participate in the program, according to UnitedHealthcare data.

Patients with diabetes are 40 percent more likely to take part in the Motion program than those without the condition. The American Diabetes Association recommends 30 minutes of moderate-to-vigorous aerobic exercise five days a week, including “brisk walking” and dancing, to manage diabetes.

In addition to health and financial incentives for beneficiaries, UnitedHealthcare said the wellness program can create financial incentives for plan sponsors as well. Study data show that companies that joined UnitedHealthcare Motion spent $222 less per member per year compared to non-Motion plans, according to the insurer.

“The savings were a result of a reduction in outpatient care (65 percent), inpatient care (29 percent) and other care (6 percent),” a spokesman said via e-mail. “For an organization with 500 employees, that translates to more than $100,000 per year in savings.”

Although the Apple Watch and other devices may capture other data like location and heart rate, UnitedHealthcare said the insurer only receives the single stream of data that it needs to measure progress in the Motion program — and users have to specifically authorize it beforehand.

“The only data we collect and use to operate the program is step data,” Sterling said.