Minnesota's biggest health care companies got even bigger last year as the sector's never-ending growth story continues.

UnitedHealth Group bolstered its position as Minnesota's largest company in 2018 by growing its health insurance and health care services businesses, while also adding to operations in South America. Reported revenue grew by 12.5% to a whopping $226.2 billion.

Medtronic, meanwhile, held on to the No. 5 spot on the Star Tribune list of top public companies with $30.6 billion in revenue, a growth of 2.8%.

"You saw strong organic growth at both businesses relative to expectations," said David Heupel, senior equity research analyst with Thrivent. "Those are the things, as a long-term investor, we're looking for."

In early 2018, Minnetonka-based UnitedHealth Group closed on its acquisition of Empresas Banmedica, a company that runs hospitals and clinics and sells insurance coverage in Chile, Peru and Colombia.

The deal added about 23,000 workers and helped push overall employment at UnitedHealth Group to 300,000 people. Back in 2012, UnitedHealth bought into the South America market by purchasing a stake in a large health care and health insurance company in Brazil.

The company's health insurance business, UnitedHealthcare, keeps getting bigger, Heupel said, particularly in the market where seniors buy Medicare Advantage health plans. Already the nation's largest health insurer, UnitedHealthcare started making a push last year to sell more coverage in its home state, where a 40-year-old ban on for-profit HMOs previously was a barrier in some markets.

Growth rates continue to be even higher at Optum, the health services division at UnitedHealth Group. It includes a pharmaceutical benefits manager, a unit that provides direct patient care and a health care data consulting arm.

"This is still a company that can grow double-digit earnings for quite a long time," Heupel said. "And a lot of that is driven by Optum."

With operational headquarters in Fridley, Medtronic continues to be the biggest player in a local cluster of medical device manufacturers that includes large operations in the Twin Cities for out-of-state players Abbott Laboratories and Boston Scientific.

In 2017, Medtronic suffered with supply problems for its next-generation continuous glucose monitor device for patients with diabetes. The supply problems were resolved last year, Heupel said, and provided a highlight. "The rest of the company also saw some stronger product launches in other areas, [although] maybe not as dramatic as what we saw in diabetes," Heupel said. "It was a year when they really put together some consistent quarters — we saw the margin expansion we wanted to."

The four other health care companies on the list also saw revenue grow: Patterson Cos. Inc. (#15); Bio-Techne Corp. (#35); Cardiovascular Systems Inc. (#45), and Tactile Systems Technology Inc. (#48).