Almost half of heart surgery patients may require temporary post-operative insulin treatment even if they do not suffer from diabetes, according to a new study.

Research from the University of Michigan Health System showed that patients who have undergone heart surgery may experience blood sugar levels high enough to require medication, with older and obese patients most at risk.

The findings, at the American Diabetes Association's Scientific Sessions in San Francisco, revealed that out of 1,362 heart and vascular surgery patients, 662 developed "stress induced hyperglycemia" and 87 required blood sugar medicines post hospitalization.

It is a known danger that high blood sugar levels during heart and vascular surgery can hinder recovery and result in a higher risk of infection and death.

In response, many patients are administered doses of insulin in the operating room during surgery.

"But high blood sugar in non-diabetic patients after surgery hasn't been fully studied," said researcher Dr Sima Saberi.

"Stress-induced hyperglycemia occurs when the body reacts to the double insults of having an operation on the heart or major blood vessels, and of being cooled down by the heart-bypass machine to protect the heart muscle during surgery."