Blood Glucose Control after Heart Surgery Decreases Risk of Infection

One of the main causes of post-cardiac surgery infection is high blood glucose, or hyperglycemia. A study led by the diabetes team of the Ottawa Heart Institute analyzed the aftermath of all cardiac surgeries to examine the effect of blood glucose levels on the occurrence of post-surgical infection. 

Heart Institute patients have significantly higher rates of diabetes and prediabetes. The study looked specifically at surgical patients who had high blood glucose levels, indicated by a hemoglobin A1C (HbA1C) of 6% or higher. About 80% of these patients’ glucose levels were regulated by IV-administered insulin during the immediate post-operative period, but only 50% were prescribed insulin upon transition to the ward and subsequently for their return home post-surgery. 

The researchers found a correlation between controlling insulin levels before and after surgery and a decreased risk of infection. Unexpectedly, infection without IV insulin administration was seen mostly in patients with an HbA1C of less than 7%—those with lower blood glucose. However, all in all, more than 25% of patients developed a post-operative infection and hyperglycemia remains the cause of complications.

The authors concluded that IV insulin control before and after cardiac surgery needs to be standardized, and should always be transitioned to subcutaneous insulin injections immediately. Such an approach will be piloted at the Heart Institute.