Toljan was brought to Celtic by Brendan Rodgers in the January transfer window.
The German newspaper claims Toljan is now the focus of Gladbach following the club's earlier capture of third-choice goalkeeper, Max Green.
The former Germany Under-21 international played 14 times for Celtic after joining from Borussia Dortmund in January.
But he lost his place under Neil Lennon - the manager who inherited him from Brendan Rodgers - and is not expected to return to Celtic Park.
Last week, Toljan expressed a desire to return to Dortmund, where he has struggled to impress since his £6.2 million transfer from Hoffenheim two years ago.
But Bild suggests he is likely to have 'no chance' of earning a reprieve back at his parent club.
As well as Toljan, Celtic have fellow right-backs Mikael Lustig and Cristian Gamboa out of contract this summer.
Celtic fans - would you take Toljan back this summer?
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