Preoperative blood glucose concentrations and postoperative outcomes after elective non-cardiac surgery: an observational study

The association between preoperative blood glucose (BG) concentration and outcomes after non-cardiac surgery and the impact of the diabetes diagnosis status remain unclear. We tested two hypotheses: that preoperative BG is related to surgical outcomes; and that this relationship depends on the diabetes diagnosis status of the patient. We retrospectively analysed data on 61 536 consecutive elective non-cardiac surgery patients treated at our tertiary care facility. Logistic regression models were used to test the hypotheses before and after adjustment for baseline patient characteristics. Our primary outcome was a composite of in-hospital serious complications and mortality. A second primary outcome was 1 yr mortality. The crude incidence of the composite in-hospital outcome was significantly related to preoperative BG (P0.001), but not after covariable adjustment (P0.40). This relationship did not significantly differ between patients with and without diagnosed diabetes (P0.09). One year mortality was significantly related to preoperative BG, both univariably (P0.001) and after covariable-adjustment (P0.001). Patients with diagnosed diabetes and preoperative euglycaemia generally had worse 1 yr mortality than those without diabetes at the same BG {e.g. odds ratio (OR) [95 confidence interval (CI)] of 1.27 (1.06, 1.53) at 6 mmol litre(1) (108 mg dl(1)), P0.003}. Conversely, hyperglycaemic patients with diagnosed diabetes displayed a significantly lower 1 yr mortality than hyperglycaemic patients without diabetes [OR (95 CI) of 0.58 (0.44, 0.77) at 12 mmol litre(1) (216 mg dl(1)), P0.001]. For elective non-cardiac surgery, preoperative hyperglycaemia should be given greater consideration in patients without diabetes than in those with diagnosed diabetes.