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Euglycemia in Diabetics Associated with Higher Risk of Long-Term Mortality from Noncardiac Surgery

Oct 28, 2010

Diabetic patients are at increased risk for death for 1 year after an elective non-cardiac operation — even if their blood glucose levels before surgery are normal according to research…. 

In contrast, hyperglycemic diabetic patients’ risk for death after elective non-cardiac surgery is low, said Basem Abdelmalak, MD, Cleveland Clinic, Cleveland, Ohio. 

After adjustment for co-variables, they found that the relationship between blood glucose levels and the likelihood of complications after surgery did not differ significantly between patients with and without diabetes (P =.048 < Bonferroni-adjusted significance criterion of 0.025). They did uncover a significant difference, however, between diabetics and nondiabetics in the relationship between preoperative blood-glucose levels and deaths during the 1-year postoperative period. A higher risk of dying from non-cardiac surgery characterized nondiabetic patients with high blood glucose levels when compared with diabetics with high blood glucose. “It is possible that nondiabetics with high blood sugar were undiagnosed and, thus, [were] untreated diabetics,” said Dr. Abdelmalak. “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.” The researchers analyzed data from 61,536 patients who had elective non-cardiac operations from January 2005 to November 2009; overall, 15.8% of these patients had diabetes. The team examined in-hospital, postsurgery cardiac, neurological, urologic, and infectious complications and death within 1 year of surgery. Additive logistic regression models were used in the analysis. For a given outcome, the researchers estimated the unadjusted and covariable-adjusted incidence as a function of preoperative blood glucose for diabetics and nondiabetics. They also adjusted for type of surgery and baseline comorbidities. The crude incidence of the composite in-hospital outcome for diabetic patients was about 15% regardless of baseline blood glucose. For nondiabetics, it ranged from 7% to 9% for euglycemic patients to 13% to 15% for patients whose blood glucose was over 150 mg/dL. Non-diabetes crude incidence was strongly related to baseline blood glucose, ranging from 3% to 5% for euglycemic patients to over 11% for patients with blood glucose higher than 200 mg/dL. After adjusting for covariables, significantly different relationships between diabetic and nondiabetic patients remained (P <.001). “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 are managed for their non-cardiac surgery.” [Presentation title: Pre-Operative Blood Glucose and Outcomes Following Non-Cardiac Surgery, Impact of Diabetes. Abstract A794]