A major health insurer is cutting costs through teaming up with health-care providers.

Highmark Inc. cut the cost of care for 2,000 of its sickest members through a new program that includes a team of Allegheny Health Network health-care providers, David Holmberg, president and chief executive officer of Highmark Health of Pittsburgh said Dec. 3.

Highmark Health owns health insurer Highmark Inc. as well as Allegheny Health System, a hospital and medical provider organization.

Within a year, the costs to...