Italy coach Antonio Conte had unveiled a 28-man squad for the matches on September 3rd and 6th, respectively.
However, Toronto FC striker Sebastian Giovinco has been forced to leave Italy's training base at Coverciano near Florence with an injury knock which the Italian federation (FIGC) say occurred while he was playing against Montreal on Saturday.
Insigne was added to the list late on Sunday night and Giovinco was given the green light to leave the squad on Monday morning.
Italy, who are second in qualifying Group H, one point behind leaders Croatia, host Malta in Florence on September 3rd and then Bulgaria three days later in Palermo.
Croatia lead Group H on 14 points from four wins and two draws so far but they have been deducted a point following a 1-1 draw with Italy in June after a swastika was scrawled on the pitch before the fixture in Zagreb.