The collection of blood samples, an essential prerequisite of laboratory diagnostics, is the most vulnerable step in the total testing process.1"3 Blood samples diluted and/or contaminated with saline (i.e., 0.9% sodium chloride), drug(especially heparin, fibrinolytic and chemotherapeutic agents) or glucose-containing solutions are relatively frequent occurrences,4 representing nearly 2% of all unsuitable specimens referred for testing.5-6 Contamination from infusion fluids more often occurs when blood is drawn from cannulae or catheters, and if an inappropriate volume of blood is not discarded before drawing the blood into primary blood collection tubes.7 Although it remains an infrequent occurrence, the analysis of contaminated samples may be associated with production of unsuitable test results, which may jeopardise the clinical and therapeutic decision-making,8 and increase healthcare expenditure.9 Among the various intravenous infusion fluids, it is widely acknowledged that blood sample contamination in patients receiving intravenous glucose-containing solutions dramatically affects the concentration of this analyte in plasma or serum. ...even a concentration of blood glucose much lower than that suggested by Hernandez may trigger inappropriate clinical and therapeutic decision-making, thus jeopardising patient safety and wasting valuable healthcare resources. ...the aim of this small study is to establish to what extent contamination with a glucose-containing solution may affect the results of some selected laboratory parameters, for which the simple and dilutional effect from exogenous fluid may not completely explain the bias.