Hyperosmolar hyperglycemic state (HHS), a life-threatening complication of diabetes mellitus, may initially manifest with a broad spectrum of neurological symptoms. These include encephalopathy, coma, chorea-hemiballismus and epileptic activity. Focal motor seizures are among the most common manifestations whilst aphasia has rarely been described so far. Based on a recent experience from our hospital, we herein report a rare case of a patient with nonketotic hyperglycemia-induced global aphasia, followed by focal motor seizures and attempt a comprehensive review of the literature with regards to the various neurological syndromes through which, undiagnosed diabetes and HHS may present. Neurological aspects of HHS are not so well-documented and are certainly under-represented in the literature.