As part of a larger randomized , single-blind , interventional efficacy study on the effects of hyperinsulinemic glucose control in cardiac surgery ( NCT00524472 ) , consenting patients were randomly assigned to receive combined administration of insulin and glucose , titrated to preserve normoglycemia ( 3.5-6 .1 mmol L ( -1 ) ; experimental group ) , or standard metabolic care ( blood glucose 3.5-10 mmol L ( -1 ) ; control group ) , during open heart surgery .