The 27-year-old Truet, a native of New Caledonia, was driving from a tournament in Decatur, Ill., to the developmental tour's next tournament in Lima, Ohio, when her car went out of control Sunday afternoon.
Her eastbound car hydroplaned across the road onto the median, back onto the highway and through the median again before striking the westbound semi, police said.
The driver of the truck, Denny E. Pollard, 52, of Charleston, Ill., was not injured.
Truet, in her third year on the tour, had a best finish of sixth in 36 career tournaments. She missed the cut in seven of nine events this year, including last week's Michelob Ultra at Hickory Point Golf Course in Decatur.
Truet was born in Noumea on the French island territory of New Caledonia in the South Pacific. She was on the golf team at Arizona State in 2001-03 and was a two-time NCAA Academic All-American.