Bret Michaels is currently being treated at a hospital in Nashville, Tennessee, ahead of one of his shows. 

The 59-year-old musician took to Instagram to express his regret for having to miss the concert. "To the incredible fans in Nashville, thank you for all your well wishes!! I was truly fired up to get on stage in the Music City and perform, but due to an unforeseen medical complication and following hospitalization, it was not possible," he wrote. "I send my deepest apologies being unable to rock the stage tonight!!! I'm working on being back 100% and hope you rocked hard with my friends Motley/Leppard/Joan and Classless Act!!!"

The rocker and Poison frontman was taken to the hospital on Thursday, shortly before his band was set to perform as part of a Stadium Tour, alongside  Def Leppard, Mötley Crüe and Joan Jett and the Blackhearts.

Several of Michaels' bandmates took to the stage during the show to inform fans of his hospitalization, and that they would therefore be unable to perform their set, according to TMZ, who first reported the news. TMZ also reported that the hospitalization may have been the result of a bad reaction to medication Michaels had been taking, which may have had unexpected side effects as a result of his Type 1 diabetes.

ET has reached out to Michaels' reps for comment.

The stadium tour is still scheduled to continue, with the next planned stop in Jacksonville, Florida, on Saturday. It's unclear if the hospitalization will impact the tour schedule.

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