A study presented during the weekend to the American Diabetes Association at its annual scientific meeting in San Diego and one published by the American Sociological Association suggest that biological and psychological factors interact in the control of blood sugar levels.

Depression affects diabetes, in part because patients are less likely to take care of themselves if they're depressed, says Patrick Lustman, professor of medical psychology at Washington University School of Medicine in St. Louis.

Lustman, who reported his findings Saturday at the San Diego meeting, compared 44 patients who had the most common type of diabetes with 44 who had diabetes and depression.