MATERIAL & METHODS: 325 patients admitted to the surgical intensive care unit after elective on-pump cardiac surgery will be consecutively enrolled. Baseline characteristics and routine blood samples will be assessed the day before surgery. Study blood samples will be drawn preoperatively in the induction bay of anesthesia to measure the insulin resistance indices HOMA and QUICKI, HbA1c, ANGPTL2, CXCL5, visfatin, and irisin. Blood glucose, irisin, adipokines, and routine biochemical tests will be assessed upon admission to the intensive care unit and on postoperative days 1 and 3. Adverse outcomes will be assessed 30 days after surgery. Sample size is set to ensure at least 80% power at a significance level of 0.05.