ANN ARBOR, Mich. - Nearly half of all heart surgery patients may experience blood sugar levels high enough to require temporary insulin treatment after their operation, even though they've never had diabetes, according to a new study from the University of Michigan Health System.

In addition, a significant minority of those patients might need to take medicines for days or weeks after they leave the hospital to help their blood sugar levels reach normal. Obese patients, older patients, and those whose blood sugar levels were still high two days after their operation are most likely to need this kind of treatment.

The study did not look at whether these patients later developed true diabetes or pre-diabetes, but the results are striking enough to warrant a new U-M research project. It will recruit patients before their operations, and will include longer follow-up and more rigorous testing of pre-surgery and post- hospitalization blood sugar levels.
A U-M team -- part of the Hospital Intensive Insulin Program led by U-M endocrinologist Roma Gianchandani, M.D. -- presented their findings at the American Diabetes Association's Scientific Sessions held in San Francisco on June 6, which featured a poster that included retrospective data from 1,362 patients who had certain heart and vascular operations at U-M in 2006 and 2007.

Findings showed that 662 patients developed "stress induced hyperglycemia" (SIH), or high blood sugar after surgery, and 87 needed blood sugar medicines when they left the hospital.

Heart and vascular surgeons know that high blood sugar during surgery is associated with unfavorable recovery and a higher risk of infection and death. Most heart and blood vessel surgery patients have their blood sugars monitored
while in the operating room, and many patients receive doses of insulin while the operation is in progress.

The new study looked at what happened after surgery, and what factors predicted a need for blood sugar treatment. By far, the most telling sign that a person was likely to need such treatment - both in the hospital and at discharge - was their average blood sugar two days after surgery.

Those patients whose glucose levels were still high at this point were more than two and a half times more likely to need post-hospital medicines, even after other factors were considered.

Patients who had a body mass index (BMI) over 35, which is consistent with a diagnosis of obesity, were also somewhat more likely to develop SIH, as were older patients. But these factors were not nearly as strongly predictive of SIH as was the glucose level on the second day after surgery.

The patients in the study had a coronary artery bypass operation, a heart valve operation, or an operation on the upper part of their aorta.

The new project, to be led by Gianchandani and Rodica Pop-Busui M.D., Ph.D., a co-author of this study, is being proposed to start later this year at U-M.

More information on the UMHS Hospital Intensive Insulin Program is available at:
www.med.umich.edu/intmed/endocrinology/staff/HIIP.htm

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