Abstract
A Morel-Lavallée lesion (MLL) is a type of closed injury resulting in the internal shearing of superficial skin and subcutaneous tissue from the underlying fascial layer, usually occurring after traumatic accidents such as sports injuries or motor vehicle accidents. In this case, a 68-year-old man developed an MLL as a complication following a moderate-impact fall due to metformin-induced vitamin B12 deficiency. A known complication of metformin use is vitamin B12 deficiency, but this is often underdiagnosed due to a lack of routine screening. This case illustrates the importance of being aware of this complication and the many roles of vitamin B12 in terms of its effects on balance, proprioception, blood vessel integrity, and wound healing, emphasizing the importance of routine vitamin B12 screening in metformin users.