Factors influencing accuracy of blood glucose measurements in critically ill patients

Introduction

Rapid and accurate blood glucose measurement is essential for treatment of critically ill patients. This prospective observational study, performed in a nine-bed medical ICU, was designed to evaluate factors affecting the accuracy of different methods of blood glucose measurement.

Methods

A total of 29 consecutively admitted patients were included. Blood glucose was measured with a glucometer (Lifescan surestep™, capillary and arterial), a blood gas analyzer (Radiometer ABL-735, arterial), and a central laboratory (Olympus AU5400, arterial). Each value was compared with the reference laboratory result. Discrepancy was defined as the percentage of paired values not in accordance (>0.83 mmol/l difference for laboratory values <4.12 mmol/l, and >20% difference for values ≥ 4.12 mmol/l). Patient demographics, and clinical data including the presence of peripheral edema, vasopressor dependence, hematocrit, arterial pH and PaO₂ were also recorded. Binary logistic regression analysis was used to determine the independent factor of discrepancy of blood glucose measurements.

Results

Discrepancy occurred in 46% (152/332) of blood glucose measurements. Independent factors of discrepancy are presented in Table 1.

Table 1 Independent factors of discrepancy of blood glucose measurements

Conclusion

Decreased hematocrit, poor oxygenation, and use of glucometer significantly increased the risk of discrepancy of glucose measurements in critically ill patients.