Martinez was dropped off by an unknown individual at Beaumont and police are investigating.
The Saginaw woman is said to be okay and resting at the hospital, but her mother declined to speak with FOX 2.
It is not known why she disappeared or why the condition required medical treatment.
Stay with FOX 2 for more information on this developing story.
Martinez, 20, had been last seen at The Official Movement Closing Party at the Detroit Masonic Temple.
Dani Welchner is a friend of Martinez and she last saw her at 3 a.m. Tuesday.
She said she last saw Grace talking to an older white male, who may have been around 40 years old. He had brown hair and brown eyes, was clean shaven and wearing a blue dress shirt.
She said he seemed out of place.
At 3 a.m. they last spoke. She and Grace agreed to meet up at the car when the party was over at 4 a.m. She never showed. Dani said she waited until 5:30 but there was no sign of her.