All glucose measurements are not equal

Dr. Rice et al. have raised a very interesting question about our article published in the March 2009 issue of Anesthesiology,1that concerns the accuracy of the glycemic measurements on capillary blood samples. We agree that the most reliable measurement for blood glucose concentration is on blood samples obtained by arterial line. Generally, the measurement of blood glucose concentration through the HemoCue B-Glucose analyzer (HemoCue, Angelhom, Sweden) with peripheral capillary blood is considered to be reliable in noncritical patients.2,3Thus, previous studies even in critical care patients have used this approach, including the one by Van den Berghe et al. that specified: “The dose of insulin was adjusted according to whole-blood glucose levels, measured at 1- to 4-h intervals in arterial blood or, when an arterial catheter was not available, in capillary blood, with the use of a point-of-care glucometer (HemoCue B-glucose analyzer, HemoCue).”4Our protocol is similar to that of Van den Berghe et al. , but we hypothesized that in our patients population, which is relatively younger than in previous studies, the risk of hypotension, hypoxia, and acidosis is lower. Nevertheless, as we have mentioned in our article, to overcome the risks of this bias we have performed the measurements of blood glucose concentration exclusively on capillary blood samples only in few cases (i.e. , patient in which was difficult to get arterial blood sample: <5% of the measurements). Thus, “in all patients, glucose concentrations were measured in whole blood or on undiluted arterial blood rather than capillary blood samples.” Furthermore, as we reported in the paper, we have made systematic cross controls between blood glucose concentration obtained by arterial and capillary samples and found in our study group nonsignificant differences between the values obtained with the two approaches.