Metformin-Induced Nightmares: An Uncommon Event.

Metformin is well-known in the treatment of type 2 diabetes mellitus (DM). Metformin has become a drug of choice due to its affordability, cost-effectiveness, and established safety record. It primarily works by inhibiting hepatic gluconeogenesis. Common side effects include gastrointestinal issues, with rare complications, such as lactic acidosis and vitamin B12 malabsorption. This study discussed a 72-year-old male with type 2 DM who experienced recurrent nightmares upon initiating metformin, which ceased after discontinuation. The mechanism of metformin-associated nightmares remains poorly understood. Despite metformin's benefits, this case highlights the importance of recognizing rare adverse effects like nightmares, which can significantly impact patients' quality of life.