TABLE 1.

CONFOUNDING FACTORS OF GLUCOSE MONITORING SYSTEMS

Factor	Mechanism of Action
Hematocrit	Red blood cell concentration alters the apparent glucose measured by biosensors. Specifically, anemic specimens yield falsely elevated results due to increased diffusion of glucose into the biosensor. Alternately, polycythemic specimens yield falsely low results due to mechanical impedance of glucose diffusion.
Non-glucose sugars	Sugars such as galactose, lactose, and maltose are Indistinguishable to certain glucose biosensors (e.g., glucose dehydrogenase) and generating falsely elevated results. Galactose may be encountered in neonates with hypergalactosemia. Maltose can be found in patients receiving peritoneal dialysis and icodextrin.
Oxidizing and reducing	Electrochemical glucose biosensors rely on oxidation and reduction reactions. The presence of oxidizing and reducing substances (e.g., ascorbic acid) affect these electrochemical reactions and produces erroneous results.
Oxygen tension (pO2)	Sample partial pressure of oxygen may alter electrochemical reaction kinetics in glucose biosensors that rely on an oxygen intermediate.
Sample pH	Glucose biosensors rely on enzymatic reactions to convert glucose into a readable signal. Abnormal pH may impair enzyme function and therefore impact glucose results.
Temperature	Both abnormal sample and environmental temperatures may affect glucose biosensors. Temperature may alter the enzymatic reaction required to produce glucose results.
User error	Inadequate blood volume, incorrect sample type, or collection of capillary blood samples in patients with systolic blood pressure of less than 90 mmHg yield inaccurate glucose results.