Neither Diabetes nor Glucose-Lowering Drugs Are Associated With Mortality After Noncardiac Surgery in Patients With Coronary Artery Disease or Heart Failure

Abstract Background It is unclear whether diabetes mellitus or use of particular glucose-lowering agents is associated with increased risk of mortality after noncardiac surgery in patients with known cardiac disease. Methods We carried out a retrospective cohort study using 4 linked administrative databases in the province of Alberta, Canada from 1999-2006. Results Of the 32,834 patients with known cardiac disease in our cohort, 9305 (28%) had diabetes. All-cause 30-day mortality after noncardiac surgery was 6.4% in patients with diabetes, and 6.1% in those without diabetes (multivariate adjusted odds ratio [aOR] 0.97, 95% confidence interval [CI], 0.87-1.08). In the 24,037 patients older than 65, mortality was 7.5% in individuals with diabetes and 7.5% in those without diabetes (5.7% in those taking insulin [aOR, 0.89; 95% CI, 0.70-1.13], 8.0% in those using oral agents only [aOR, 1.08; 95% CI, 0.95-1.22]). None of the glucose-lowering drug classes were associated with perioperative mortality in elderly cardiac patients (sulfonylureas aOR, 0.94; 95% CI, 0.76-1.16; metformin aOR, 0.92; 95% CI, 0.74-1.14; thiazolidinediones aOR, 0.64; 95% CI, 0.40-1.04; insulin aOR, 0.83; 95% CI, 0.65-1.08), but use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (aOR, 0.83; 95% CI, 0.75-0.93), β-blockers (aOR, 0.82; 95% CI, 0.72-0.93), or statins (aOR, 0.65; 95% CI, 0.55-0.78) in the 100 days before surgery were associated with lower 30-day mortality. Conclusions Neither diabetes nor exposure to common classes of glucose-lowering drugs preoperatively were associated with increased perioperative mortality in cardiac patients undergoing noncardiac surgery. However, cardiac patients not using angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, β-blockers, or statins preoperatively exhibited higher mortality rates, emphasizing the importance of optimizing evidence-based therapy before elective surgery in these patients.