Coleman, 19, has yet to play for the Iron's first-team but may find opportunities easier to come by following the departure of Marcus Williams to Reading.
Coleman had loan spells in non-league last season with Harrogate Town and Ilkeston, and said his target for next season was to be involved in matchday squads.
He cited the success of Niall Canavan, who broke into the senior squad during the latter part of last season.
"I want to try and force my way into the squad now, Niall's done really well since coming into the side," he told United's official website.
"I was a bit disappointed not to be involved last year, but that's part and parcel of being a footballer. This year if I do well in pre-season I'll get a chance."