The narrator of this novel is what is known as "unreliable" although not for the usual reasons one uses this term. Normally an unreliable narrator cannot be trusted to give the whole story because they may be dishonest, or ignorant of the truth, or intentionally trying to deceive their audience. They may also be sociopathic or insane. In Offred's case, it is possible, given the extreme controlling nature of the society she lives in, that her every communication and movement is watched by the government. And so maybe her entire story is being coerced. Also, we learn at the book's end in a strange epilogue that her story was a "found" record of some kind, and its provenance is portrayed as dubious, even as the circumstances she portrays have apparently become even more pronounced in the future society discussing her manuscript.