A half-century-old diabetes drug appears to help treat bipolar disorder by reversing patients' insulin resistance. Bipolar patients who responded to the drug metformin experienced improvement in their mood disorder as their insulin resistance decreased, said Dr. Cynthia Calkin. "We saw this improvement as early as week six in the study," she said. "Week 14 was the study endpoint, and patients remained significantly improved or in remission." Calkin noted that some patients who started off in the trial are still in remission, six or seven years later. Metformin helps treat type 2 diabetes by reducing production of glucose by the liver...