CHICAGO (AP) — Marvin Isley, the bass player who helped give R&B powerhouse the Isley Brothers their distinctive sound, has died at a Chicago hospital. He was 56.

Isley died Sunday morning at an inpatient hospice at Weiss Memorial Hospital, according to hospital spokeswoman Catherine Gianaro. She could not confirm a cause of death.

Isley stopped performing in 1996 after suffering complications from diabetes that included a stroke, high blood pressure, the loss of both legs and use of his left hand.

He joined his brothers’ band in 1973. By that time, the Isley Brothers had established themselves with hits like 1959’s “Shout,” which sold more than 1 million records. Isley splintered off to form Isley-Jasper-Isley in the 1980s and returned to the Isley Brothers in the 1990s. The group was inducted into the Rock and Roll Hall of Fame in 1992, and their career has spanned six decades.

At one point there were five Isley brothers in the group, including Marvin. Today, only Ronald Isley is touring full time after a three-year stint in federal prison for tax evasion.

The group’s hits included “Twist and Shout,” later recorded by The Beatles, “Love The One You’re With,” and the Grammy-winning 1969 smash, “It’s Your Thing.”

In a 2001 interview, Marvin Isley told the Atlanta Journal-Constitution he regretted spending decades ignoring his diabetes.

“If I would have listened, if I would have understood diabetes like I understood music, maybe these things wouldn’t have happened,” Isley said at the time.

In 2000, he settled a lawsuit against his older siblings stemming from a dispute over money from the estate of his deceased older brother, O’Kelly Isley, and from a $7 million plagiarism award against Michael Bolton relating to the group’s 1966 song “Love Is A Wonderful Thing.”

Funeral arrangements were not immediately available.