BB King has apologised to fans after an erratic performance led to a stream of audience catcalls and early departures.
The Rock and Roll Hall of Famer issued a public apology for what his publicists called "a bad night for one of America's living blues legends".
The written statement said the blues guitarist, 88, and his band had returned from a four-week break before the show at the Peabody Opera House on April 4.
The band drove straight to eastern Missouri from Las Vegas, a 24-hour, 1,600-mile trip each way. And King missed his daily dosage of diabetes medicine, which elevated his blood sugar.
"The combination of the rigors of the very long drive and high blood sugar due to his medication error resulted in a performance that did not match Mr King's usual standard of excellence," read the statement, which was issued on behalf of King by the St Louis venue. "Mr King apologises and humbly asks for the understanding of his fans."
Concert-goers said the star's rambling set featured just a handful of complete songs amid meandering musical snippets, long-winded soliloquies, an eight-piece back-up band that missed its cues and a 15-minute sing-along of You Are My Sunshine.