Performance Requirements for Glucose Assays in Intensive Care Units

Treatment of patients in the intensive care unit (ICU)2 with intravenous insulin became popular after initial reports suggesting that such treatment led to decreased in-hospital and 30-day mortality (1–3). Such treat-ment became controversial when several subsequent studies failed to confirm the improved clinical out-comes (4–6). The latter studies, however, used differ-ent methods for glucose measurement, and the mea-surements typically were made less frequently (7). If we wish to optimize glucose monitoring in pa-tients being treated with intravenous insulin while in the intensive care unit, we need answers to several questions: 1) How frequently should glucose be mea-sured? 2) What quality of glucose measurement is needed? 3) What protocol should be used to guide in-sulin treatment? 4) How much nursing time will be required to conduct such monitoring? 5) Will such monitoring lead to improved outcomes? This editorial concerns itself primarilywith the first 3 of these, but the last 2 are extremely important considerations in the clinical arena. Computer simulation studies offer several advan-tages for answering such questions. First, they entail no risk to patients. Second, many thousands (or millions) of patient-care episodes can be simulated; moreover, various treatment protocols and the effects of different measurement frequencies can be considered simulta-neously with evaluation of the analytical requirements for glucose assays. Finally, simulations can predict sur-rogate markers of patient outcomes such as rates of hypoglycemia and hyperglycemia, time in range, and within-patient variation of glycemia. This issue of Clinical Chemistry contains 2 reports of novel computer simulation studies of glycemic con-trol in ICU patients (8, 9). These studies may help to answer questions regarding what analytical quality is required of glucose assays, and what impact more-frequentmeasurement has onpatient outcomes and/or the analytical performance requirements of glucose measurement. Although earlier modeling studies of these questions have used established physiologic models of glucose homeostasis (10, 11), what makes the current modeling studies unique and so important is that the models in these studies are based on data from actual ICU patients