Diemer began her career as a painter. Her early works from the late 1960s are paintings inspired by her professor at the academy, Richard Mortensen, one of Denmark’s most influential and innovative artists of abstract art.
Since the 1970s, photography has been central to her work. In the 1980s her photographic work introduced myths and iconography from the Inuit and Ancient Greece, often with motives of female classical sculptures, one consisting figure being the goddess Athena. Diemer often produces her motives in multiple editions and several different media with color variations. Playing with figure/ground relations and the interactions of color, Diemer presents the viewer an archetypal female image that reflects the changing perspectives of different historic perceptions of women, conveying a multitude of dynamic, visual sensations and encouraging us to think about how idealised images of the female body measures up against the figures of real, living women.