Researchers have warned for years that melatonin can weaken the body's insulin response. For a 64-year-old woman with a rare insulin-producing tumor, that same effect may have worked in her favor.
In a case report published in JCEM Case Reports in April 2026, Thanh Nguyen and Aleksey Matveyenko of Mayo Clinic and Galina Smushkin of the University of British Columbia describe a patient whose dangerous blood sugar crashes became far less frequent after she began taking over-the-counter melatonin for sleep. The tumor later removed from her pancreas contained melatonin receptors, offering a possible explanation for what her glucose monitor recorded.
