The psychiatric conditions secondary to substance use (whether legal or illegal drugs) are well characterized and include psychosis, mania, depression and behavior changes.

We present a case of metformin-induced psychosis in a 79 years-old patient without any previous psychiatric history.

She was brought to emergency room after suicide attempt by hanging. She had a one-month history of altered behavioral and presented paranoid delusional though. Hallucinations were excluded. A detailed clinical evaluation excluded dementia, late-onset chronic psychosis and primary mood disorders with psychotic symptoms and revealed that symptoms initiate few days after the introduction of metformin to treat her diabetes. After Metformin suspension, total remission of psychotic symptoms was obtained in one week and patient return to previous functionality.

Psychosis secondary to metformin use is a very rare complication of oral antidiabetic drugs use but the awareness of this condition can lead to an earlier recognition and diagnosis.