['The authors investigated whether an insulin protocol for parenteral nutrition (PN)-induced hyperglycemia is superior to conventional management relying primarily on sliding-scale insulin at a large county hospital.', 'A prospective cohort study with historical controls was completed. Adult patients receiving PN were managed with a protocol that determined insulin doses based on carbohydrate delivery and capillary blood glucose (CBG) if half or more of CBG measurements in the first 24 hours after initiation of PN exceeded 140 mg/dL. Control data were obtained from records of patients who met study eligibility criteria but had been managed before implementation of the insulin protocol.', 'Mean CBG after the start of insulin therapy was 138 ± 37 mg/dL for protocol patients and 159 ± 46 mg/dL for controls (P < .0001). Proportion of CBG values in the target range of 80-140 mg/dL was 60% in the protocol group and 35% in the control group (P < .0001). Hypoglycemia, defined as CBG <80 mg/dL, occurred infrequently but more often in the protocol group (3% vs 1%, P = .012). There was no difference in total daily insulin between groups, although protocol patients received mostly scheduled insulin (93% total daily dose), whereas control patients received predominantly supplemental insulin (66% total daily dose).'] Is an insulin protocol for management of hyperglycemia in patients receiving parenteral nutrition superior to ad hoc management?