Harken Health, the Minnetonka-based insurer that offers free primary care at company-owned clinics, says it will add eight new health centers in Chicago and Atlanta by 2017.

Launched late last year, Harken Health is an independent subsidiary of UnitedHealthcare that is focused on the individual market, including customers on new government-run health insurance exchanges.

The subsidiary's growth on the exchanges makes for an intriguing juxtaposition with UnitedHealthcare, which is retreating from the exchange markets in some two dozen states following financial losses.

"We had an overwhelmingly strong response to our model, which exceeded our expectations," said Tom Vanderheyden, the chief executive at Harken Health, in a statement.

In a regulatory filing this month, Harken Health said about 33,000 people were enrolled in the company's health plans by the end of the first quarter. The insurer started selling coverage Jan. 1, and collected about two-thirds of its $30.6 million in first-quarter premium revenue in Illinois.

Subscribers can get primary care with no copays so long as they get treatment from one of Harken Health's clinics, which the company calls "health centers."

Harken Health currently operates four health centers in Cook County, Illinois, where the insurer plans to open another six clinics by next year. Harken currently has six clinics in the Atlanta area, where it plans to open two more by 2017.

In addition to primary care, the health centers also offer everything from sessions with "health coaches" to classes in nutrition, tai chi and yoga.

"We have additional expansion news coming in a few weeks, but aren't ready to provide further detail on which markets we are entering," Vanderheyden said Monday in a statement.

UnitedHealthcare is the nation's largest health insurer. Its parent company, UnitedHealth Group, has provided about $65 million in capital to create Harken Health.

When UnitedHealth Group last month announced that its primary insurance division would drop out of most health insurance exchanges where it currently sells policies, UnitedHealth CEO Stephen Hemsley said Harken Health was on a different track.

"Harken is a small and interesting innovation that we are considering and we will stay with it," Hemsley told investors. "It's in a very modest pilot position."

Twitter: @chrissnowbeck