The AHRQ report says in 2006 about 1.4 million hospitalizations involved patients who were admitted for a mental illness, while another 7.1 million patients had a mental disorder in addition to the physical condition for which they were admitted. The 8.5 million hospitalizations involving patients with mental illness represented about 22% of the overall 39.5 million hospitalizations in 2006.

AHRQ's analysis has found that of the nearly 1.4 million hospitalizations specifically for treatment of a mental disorder in 2006, almost 730,000 involved depression or other mood disorders, such as bipolar disease - schizophrenia and other psychotic disorders caused another 381,000 - delirium which can cause agitation or inability to focus attention, dementia, amnesia and other cognitive problems accounted for 131,000 - anxiety disorders and adjustment disorders, stress-related illnesses that can affect feeling, thoughts, and behaviours accounted for another 76,000 and the remaining 34,000 hospitalizations involved attention-deficit disorder, disruptive behaviour, impulse control, personality disorders, or mental disorders usually diagnosed in infancy or later childhood.

The figures are based on data from 'Hospital Stays Related to Mental Health, 2006' and the report uses statistics from the 2006 Nationwide Inpatient Sample, a database of hospital inpatient stays that is nationally representative of inpatient stays in all short-term, non-Federal hospitals. The data comes from hospitals that comprise 90% of all discharges in the United States and include all patients, regardless of insurance type, as well as the uninsured.

Evette Joy Ludman, Ph.D., senior research associate at the Group Health Center for Health Studies in Seattle, said that although the link between depression and diabetes complications might seem daunting, it is possible for adults to follow treatment orders for their depression while also managing their diabetes.

"I think it is a reasonable expectation that health care teams can help patients who have both depression and diabetes manage both conditions," she said. "I don't think patients see themselves as a collection of different illnesses and if we take a more proactive, integrated approach to caring for them, it is likely they can benefit. Research currently in the field is addressing that exact question."

General Hospital Psychiatry is a peer-reviewed research journal published bimonthly by Elsevier Science. For information about the journal, contact Wayne Katon, M.D., at (206) 543-7177.

Richardson LK, et al. Longitudinal effects of depression on glycemic control in veterans with type 2 diabetes. General Hosp Psychiatry , 30(6), 2008.