Normal Blood Glucose Levels in Diabetics Presenting for Surgery Were Associated with Increased Mortality from Non-Cardiac Surgery as Compared with Non-Diabetics

A clinical study presented at ANESTHESIOLOGY 2010 discovered that diabetics who presented for non-cardiac surgery with near normal blood sugar levels were at increased risk of death, as compared with their non-diabetic counterparts.

Researchers at Cleveland Clinic looked at the relationship between blood sugar levels before surgery and the occurrence of complications and death after non-cardiac surgeries, comparing the relationship between those with diabetes and those without.

The study found that the relationship between blood sugar levels and the likelihood of complications after surgery was not significantly different between diabetics and non-diabetics. However, the research showed a significant difference between diabetics and non-diabetics in terms of the relationship between blood sugar levels before surgery and deaths within one year of surgery. Non-diabetic patients with high blood sugar levels had a higher risk of dying from non-cardiac surgery compared with diabetics with high blood sugar levels. Conversely, normal blood sugar levels in diabetics were associated with a higher risk of death within one year after non-cardiac surgery versus non-diabetics.　

"It is possible that non-diabetics with high blood sugar were undiagnosed and thus, untreated diabetics," said Basem Abdelmalak, M.D., study investigator and Staff Anesthesiologist and Director of Anesthesia for Bronchoscopic Surgery at Cleveland Clinic. "It is also possible that diabetics who have lived with high blood sugar for long periods of time have become accustomed to this state and may have reset their metabolism, becoming unable to tolerate lower blood glucose levels. This is similar to what happens to patients with long-term high blood pressure."

About the Study
Researchers used specific data from surgeries on 61,536 patients who had elective surgery between January 2005 and November 2009. Overall, 15.8 percent had diabetes.　

The study examined two main outcomes: in-hospital complications after surgery (including cardiac, neurological, urologic and infectious complications) and death within one year of surgery. The study analyzed such associations using both crude and adjusted figures. The adjusted figures took into account other factors that may have contributed to poor outcomes, such as age and heart disease.

"The usual treatment goal for diabetics is maintaining normal blood sugar levels," said Dr. Abdelmalak. "However, knowledge of a higher risk of dying may stimulate further research that potentially could affect how diabetics with hyperglycemia (high sugar) are managed for their non-cardiac surgery."