How well do Space Marines get along with Imperial Guard troopers/ commissars? (spoilers maybe)?

My knowledge of it so far is only in the Gaunt's Ghosts series, particularly Salvation's Reach. Simply put Gaunt describes them as being more animal than man although certain ones (like Veegum from the White Scars) were the most human that a Space Marine could be. Throughout the book we see that the 3 recruited Space Marines treat everyone like trash, although Sar Af helps out Merrt and speaks with Ezrah and Mkoll. Later on they even listen to Ludd (who is just a new young commissar) and communicate with Kolea. If a chapter and a regular imperial guard regiment work together do the space marines even bother with paying attention to commissars in general or do they just disdain them? Are they willing to treat IG infantry as meat shields for their personal defence or will they treat the soldiers as equals? The upcoming book titled The Warmaster will take Gaunt to Urdesh along with Macaroth so I'm expecting that they will work alongside Marines at that point.