Postoperative infections, including pneumonia, wound infection, urinary tract infection and sepsis (systemic blood infection), can lead to poor outcomes and high health care costs, according to background information in the article. The risk of infection is higher in patients with diabetes. Controlling blood sugar has been shown to reduce many of the complications associated with diabetes, including kidney, nerve and eye diseases. However, previous studies have not examined whether controlling blood sugar before surgery can affect outcomes afterward.
Annika S. Dronge, M.D., Yale University School of Medicine, West Haven, Conn., and colleagues examined the relationship between glycemic (blood sugar) control and postoperative infections in 490 diabetic patients. All of the participants underwent major noncardiac surgery in the Veterans Affairs Connecticut Healthcare System between Jan. 1, 2000, and Sept. 30, 2003, and had their hemoglobin (Hb A1c) levels measured within 180 days prior to surgery. Hb A1c reflects the patient's control of blood glucose levels over the previous two to three months. Good glycemic control was defined as meeting the American Diabetes Association target, an Hb A1c level of less than 7 percent.
The patients had an average age of 71 years and 197 (40 percent) had good glycemic control. Those who did not have good glycemic control had higher rates of infectious complications after surgery, as did those who were older, had higher scores on physical status tests, had wounds that were classified as "nonclean" or had operations that took longer.
There could be two reasons for the association between glycemic control and infections, the authors write. One is that patients with better preoperative glycemic control are likely to have lower blood sugar levels after surgery as well, which has been shown in other studies to reduce risk of infection. "The other possibility for decreased postoperative infection with long-term glucose control is the overall improvement in general health and metabolic milieu of the well-controlled diabetic patient," the authors write.
"In conclusion, this study confirmed an association between tight preoperative glucose control, as indicated by Hb A1c levels less than 7 percent, and a decreased risk of postoperative infections across a spectrum of surgical cases," they conclude. "If the association is confirmed in other studies, strategies to improve glycemic control prior to elective surgery can be employed to decrease infections and improve overall outcomes for diabetic surgical patients."
(Arch Surg. 2006;141:375-380. Available pre-embargo to the media at www.jamamedia.org.)